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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 articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurement of the polarizations of prompt and non-prompt [Formula presented] and ψ(2S) mesons produced in pp collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 858, ISSN: 0370-2693The polarizations of prompt and non-prompt [Formula presented] and ψ(2S) mesons are measured in proton-proton collisions at s=13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3fb−1. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, λϑ, is measured as a function of the transverse momentum, pT, of the charmonium states, in the 25–120 and 20–100 GeV ranges for the [Formula presented] and ψ(2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for pT≳25GeV, the non-prompt [Formula presented] and ψ(2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for pT exceeding 30 times the [Formula presented] mass, where λϑ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at s=7 TeV, the prompt polarizations show a significant variation with pT, at low pT.
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Journal articleAalbers J, Akerib DS, Al Musalhi AK, et al., 2024,
The data acquisition system of the LZ dark matter detector: FADR
, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 1068, ISSN: 0168-9002The Data Acquisition System (DAQ) for the LUX-ZEPLIN (LZ) dark matter detector is described. The signals from 745 PMTs, distributed across three subsystems, are sampled with 100-MHz 32-channel digitizers (DDC-32s). A basic waveform analysis is carried out on the on-board Field Programmable Gate Arrays (FPGAs) to extract information about the observed scintillation and electroluminescence signals. This information is used to determine if the digitized waveforms should be preserved for offline analysis. The system is designed around the Kintex-7 FPGA. In addition to digitizing the PMT signals and providing basic event selection in real time, the flexibility provided by the use of FPGAs allows us to monitor the performance of the detector and the DAQ in parallel to normal data acquisition. The hardware and software/firmware of this FPGA-based Architecture for Data acquisition and Realtime monitoring (FADR) are discussed and performance measurements are described.
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Journal articleHori M, 2024,
Status of laser spectroscopy measurements of long-lived antiprotonic and pionic helium atoms at CERN and PSI
, International Journal of Modern Physics A, ISSN: 0217-751X<jats:p> The results of laser spectroscopy experiments of antiprotonic helium atoms carried out at the Antiproton Decelerator of CERN, and pionic helium atoms measured at the 590[Formula: see text]MeV ring cyclotron facility of the Paul Scherrer Institute are reviewed. The former experiment determined the antiproton-to-electron mass ratio as [Formula: see text]. In the latter, a resonant transition [Formula: see text] of pionic helium at a frequency of [Formula: see text][Formula: see text]GHz was detected. Some future perspectives are briefly described. </jats:p>
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for production of a single vectorlike quark decaying to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi><mml:mi>H</mml:mi></mml:math> or <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>t</mml:mi><mml:mi>Z</mml:mi></mml:math> in the all-hadronic final state in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mi>p</mml:mi></mml:math> 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: 110, ISSN: 2470-0010<jats:p>A search for electroweak production of a single vectorlike <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>T</a:mi></a:math> quark in association with a bottom (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>b</c:mi></c:math>) quark in the all-hadronic decay channel is presented. This search uses proton-proton collision data at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msqrt><e:mi>s</e:mi></e:msqrt><e:mo>=</e:mo><e:mn>13</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>TeV</e:mi></e:math> collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mn>138</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:msup><g:mi>fb</g:mi><g:mrow><g:mo>−</g:mo><g:mn>1</g:mn></g:mrow></g:msup></g:math>. The <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>T</i:mi></i:math> quark is assumed to have charge <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mn>2</k:mn><k:mo>/</k:mo><k:mn>3</k:mn></k:math> and decay to a top (<m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>t</m:mi></m:math>) quark and a Higgs (<o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>H</o:mi></o:math>) or <q:math xmlns:q=&
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Search for the lepton-flavor violating decay <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi>B</mml:mi><mml:mi>s</mml:mi><mml:mn>0</mml:mn></mml:msubsup><mml:mo stretchy="false">→</mml:mo><mml:mi>ϕ</mml:mi><mml:msup><mml:mi>μ</mml:mi><mml:mo>±</mml:mo></mml:msup><mml:msup><mml:mi>τ</mml:mi><mml:mo>∓</mml:mo></mml:msup></mml:math>
, Physical Review D, Vol: 110, ISSN: 2470-0010<jats:p>A search for the lepton-flavor violating decays <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msubsup><a:mi>B</a:mi><a:mi>s</a:mi><a:mn>0</a:mn></a:msubsup><a:mo stretchy="false">→</a:mo><a:mi>ϕ</a:mi><a:msup><a:mi>μ</a:mi><a:mo>±</a:mo></a:msup><a:msup><a:mi>τ</a:mi><a:mo>∓</a:mo></a:msup></a:math> is presented, using a sample of proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"><d:mn>9</d:mn><d:mtext> </d:mtext><d:mtext> </d:mtext><d:msup><d:mi>fb</d:mi><d:mrow><d:mo>−</d:mo><d:mn>1</d:mn></d:mrow></d:msup></d:math>. The <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mi>τ</f:mi></f:math> leptons are selected using decays with three charged pions. No significant excess is observed, and an upper limit on the branching fraction is determined to be <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:mi mathvariant="script">B</h:mi><h:mrow><h:mo stretchy="false">(</h:mo><h:msubsup><h:mi>B</h:mi><h:mi>s</h:mi><h:mn>0</h:mn></h:msubsup><h:mo stretchy="false">→</h:mo><h:mi>ϕ</h:mi><h:msup><h:mi>μ</h:mi><h:mo>±</h:mo></h:msup><h:msup><h:mi>τ</h:mi><h:mo>∓</h:mo></h:msup&
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math> Boson Decay to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>τ</mml:mi><mml:mi>τ</mml:mi><mml:mi>μ</mml:mi><mml:mi>μ</mml:mi></mml:mrow></mml:math> in Proton-Proton Collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msqrt><mml:mrow><mml:mi>s</mml:mi></mml:mrow></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:mrow></mml:math>
, Physical Review Letters, Vol: 133, ISSN: 0031-9007<jats:p>The first search for the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>Z</a:mi></a:math> boson decay to <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>τ</c:mi><c:mi>τ</c:mi><c:mi>μ</c:mi><c:mi>μ</c:mi></c:math> at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>138</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>fb</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>1</e:mn></e:mrow></e:msup></e:mrow></e:math>. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>Z</g:mi><g:mo stretchy="false">→</g:mo><g:mrow><g:mi>τ</g:mi><g:mi>τ</g:mi><g:mi>μ</g:mi><g:mi>μ</g:mi></g:mrow></g:math> to <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mi>Z</j:mi><j:mo stretchy="false">→</j:mo><j:mrow><j:mn>4</j:mn><j:mi>μ</j:mi></j:mrow></j:math> branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two mu
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Observation of Enhanced Long-Range Elliptic Anisotropies Inside High-Multiplicity Jets in pp Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 133A search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of sqrt[s]=13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Jets are reconstructed with the anti-k_{T} algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity |η^{jet}|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations (Δϕ^{*} and Δη^{*}) in a jet coordinate basis, where particles' η^{*}, ϕ^{*} are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to N_{ch}^{j}≈100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for |Δη^{*}|>2. For low-N_{ch}^{j} jets, the long-range elliptic anisotropic harmonic, v_{2}^{*}, is observed to decrease with N_{ch}^{j}. This trend is well described by Monte Carlo event generators. However, a rising trend for v_{2}^{*} emerges at N_{ch}^{j}≳80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Precision measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi mathvariant="normal">Ξ</mml:mi><mml:mi>b</mml:mi><mml:mo>−</mml:mo></mml:msubsup></mml:math> baryon lifetime
, Physical Review D, Vol: 110, ISSN: 2470-0010<jats:p>A sample of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>p</a:mi><a:mi>p</a:mi></a:math> collision data, corresponding to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>5.5</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> and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msubsup><e:mi mathvariant="normal">Ξ</e:mi><e:mi>b</e:mi><e:mo>−</e:mo></e:msubsup></e:math> baryon to that of the <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msubsup><h:mi mathvariant="normal">Λ</h:mi><h:mi>b</h:mi><h:mn>0</h:mn></h:msubsup></h:math> baryon, <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msub><k:mi>r</k:mi><k:mi>τ</k:mi></k:msub><k:mo>≡</k:mo><k:msub><k:mi>τ</k:mi><k:msubsup><k:mi mathvariant="normal">Ξ</k:mi><k:mi>b</k:mi><k:mo>−</k:mo></k:msubsup></k:msub><k:mo>/</k:mo><k:msub><k:mi>τ</k:mi><k:msubsup><k:mi mathvariant="normal">Λ</k:mi><k:mi>b</k:mi><k:mn>0</k:mn></k:msubsup></k:msub></k:math>. The value <o:math xmlns:o="http://www
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for Higgs boson pair production with one associated vector boson in proton-proton collisions at s = 13 TeV
, Journal of High Energy Physics, Vol: 2024A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb−1. Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the bb¯bb¯ decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, kλ, assuming k2V = 1, and vice versa on the coupling of two Higgs bosons with two vector bosons, k2V. The observed (expected) 95% confidence intervals of these coupling modifiers are −37.7 < kλ < 37.2 (−30.1 < kλ < 28.9) and −12.2 < k2V < 13.5 (−7.2 < k2V < 8.9), respectively.
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Journal articleZhang C, Zennamo J, Zamorano B, et al., 2024,
Scintillation light in SBND: simulation, reconstruction, and expected performance of the photon detection system
, European Physical Journal C, Vol: 84, ISSN: 1434-6044SBND is the near detector of the Short-Baseline Neutrino program at Fermilab. Its location near to the Booster Neutrino Beam source and relatively large mass will allow the study of neutrino interactions on argon with unprecedented statistics. This paper describes the expected performance of the SBND photon detection system, using a simulated sample of beam neutrinos and cosmogenic particles. Its design is a dual readout concept combining a system of 120 photomultiplier tubes, used for triggering, with a system of 192 X-ARAPUCA devices, located behind the anode wire planes. Furthermore, covering the cathode plane with highly-reflective panels coated with a wavelength-shifting compound recovers part of the light emitted towards the cathode, where no optical detectors exist. We show how this new design provides a high light yield and a more uniform detection efficiency, an excellent timing resolution and an independent 3D-position reconstruction using only the scintillation light. Finally, the whole reconstruction chain is applied to recover the temporal structure of the beam spill, which is resolved with a resolution on the order of nanoseconds.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Searches for violation of Lorentz invariance in top quark pair production using dilepton events in 13 TeV proton-proton collisions
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 857, ISSN: 0370-2693A search for violation of Lorentz invariance in the production of top quark pairs (tt‾) is presented. The measured normalized differential tt‾ production cross section, as a function of the sidereal time, is examined for potential modulations induced by Lorentz-invariance breaking operators in an effective field theory extension of the standard model (SM). The cross section is measured from collision events collected by the CMS detector at a center-of-mass-energy of 13 TeV, corresponding to an integrated luminosity of 77.8 fb−1, and containing one electron and one muon. The results are found to be compatible with zero, in agreement with the SM, and are used to place upper limits at 68% confidence level on the magnitude of the Lorentz-violating couplings ranging from 1–8×10−3. This is the first precision test of the isotropy in special relativity with top quarks at the LHC, restricting further the bounds on such couplings by up to two orders of magnitude with respect to previous searches conducted at the Tevatron.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
K<inf>S</inf><sup>0</sup> and Λ(Λ‾) two-particle femtoscopic correlations in PbPb collisions at s<inf>NN</inf>=5.02TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 857, ISSN: 0370-2693Two-particle correlations are presented for KS0, [Formula presented], and [Formula presented] strange hadrons as a function of relative momentum in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The dataset corresponds to an integrated luminosity of 0.607nb−1 and was collected using the CMS detector at the CERN LHC. These correlations are sensitive to quantum statistics and to final-state interactions between the particles. The source size extracted from the KS0KS0 correlations is found to decrease from 4.6 to 1.6 fm in going from central to peripheral collisions. Strong interaction scattering parameters (i.e., scattering length and effective range) are determined from the [Formula presented] and [Formula presented] (including their charge conjugates) correlations using the Lednický–Lyuboshitz model and are compared to theoretical and other experimental results.
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Journal articleHeidt C, Hanson GG, Coney LR, et al., 2024,
Transverse emittance reduction in muon beams by ionization cooling
, Nature Physics, Vol: 20, Pages: 1558-1563, ISSN: 1745-2473Accelerated muon beams have been considered for the next-generation studies of high-energy lepton–antilepton collisions and neutrino oscillations. However, high-brightness muon beams have not yet been produced. The main challenge for muon acceleration and storage stems from the large phase-space volume occupied by the beam, derived from the production mechanism of muons through the decay of pions. The phase-space volume of the muon beam can be decreased through ionization cooling. Here we show that ionization cooling leads to a reduction in the transverse emittance of muon beams that traverse lithium hydride or liquid hydrogen absorbers in the Muon Ionization Cooling Experiment. Our results represent a substantial advance towards the realization of muon-based facilities that could operate at the energy and intensity frontiers.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurement of the production cross section of a Higgs boson with large transverse momentum in its decays to a pair of τ leptons in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 857, ISSN: 0370-2693A measurement of the production cross section of a Higgs boson with transverse momentum greater than 250 GeV is presented where the Higgs boson decays to a pair of τ leptons. It is based on proton-proton collision data collected by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb−1. Because of the large transverse momentum of the Higgs boson the τ leptons from its decays are boosted and produced spatially close, with their decay products overlapping. Therefore, a dedicated algorithm was developed to reconstruct and identify them. The observed (expected) significance of the measured signal with respect to the standard model background-only hypothesis is 3.5 (2.2) standard deviations. The product of the production cross section and branching fraction is measured to be 1.64−0.54+0.68 times the standard model expectation. The fiducial differential production cross section is also measured as functions of the Higgs boson and leading jet transverse momenta. This measurement extends the probed large-transverse-momentum region in the ττ final state beyond 600 GeV.
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Journal articleFujii Y, Sasaki R, Chadeau N, et al., 2024,
Particle identification using plastic scintillators in the COMET Phase-I experiment
, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol: 1067, ISSN: 0168-9002The COMET (COherent Muon to Electron Transition) Phase-I experiment aims to search for muon to electron conversion with a single event sensitivity of O (10−15). In COMET, a Cylindrical Trigger Hodoscope (CTH), consisting of segmented plastic scintillators, provides a primary trigger signal and timing measurement while suppressing backgrounds under the high rate environment. This paper studies the particle identification capability of CTH to suppress one of the serious backgrounds induced by cosmic-rays. We demonstrated that a background suppression factor greater than 10 is achievable with a signal efficiency higher than 90%.
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Journal articleBogomilov M, Tsenov R, Vankova-Kirilova G, et al., 2024,
Publisher Correction: Transverse emittance reduction in muon beams by ionization cooling
, Nature Physics, Vol: 20, ISSN: 1745-2473 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Observation of New Charmonium or Charmoniumlike States in B^{+}→D^{*±}D^{∓}K^{+} Decays.
, Phys Rev Lett, Vol: 133A study of resonant structures in B^{+}→D^{*+}D^{-}K^{+} and B^{+}→D^{*-}D^{+}K^{+} decays is performed, using proton-proton collision data at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb^{-1}. A simultaneous amplitude fit is performed to the two channels with contributions from resonances decaying to D^{*-}D^{+} and D^{*+}D^{-} states linked by C parity. This procedure allows the C parities of resonances in the D^{*±}D^{∓} mass spectra to be determined. Four charmonium or charmoniumlike states are observed decaying into D^{*±}D^{∓}: η_{c}(3945), h_{c}(4000), χ_{c1}(4010), and h_{c}(4300), with quantum numbers J^{PC} equal to 0^{-+}, 1^{+-}, 1^{++}, and 1^{+-}, respectively. At least three of these states have not been observed previously. In addition, the existence of the T_{c[over ¯]s[over ¯]0}^{*}(2870)^{0} and T_{c[over ¯]s[over ¯]1}^{*}(2900)^{0} resonances in the D^{-}K^{+} mass spectrum, already observed in the B^{+}→D^{+}D^{-}K^{+} decay, is confirmed in a different production channel.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for bottom-type vectorlike quark pair production in dileptonic and fully hadronic 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: 110, ISSN: 2470-0010<jats:p>A search is described for the production of a pair of bottom-type vectorlike quarks (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>B</a:mi></a:math> VLQs) with mass greater than 1000 GeV. Each <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>B</c:mi></c:math> VLQ decays into a <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>b</e:mi></e:math> quark and a Higgs boson, a <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mi>b</g:mi></g:math> quark and a <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mi>Z</i:mi></i:math> boson, or a <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mi>t</k:mi></k:math> quark and a <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mi>W</m:mi></m:math> boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>Z</o:mi></o:math> boson decay. The products of the <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>H</q:mi><q:mo stretchy="false">→</q:mo><q:mi>b</q:mi><q:mi>b</q:mi></q:math> boson decay and of the hadronic <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi>Z</t:mi></t:math> or <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"><
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Journal articleArmano M, Audley H, Baird J, et al., 2024,
Tilt-to-length coupling in LISA Pathfinder: Long-term stability
, Physical Review D, Vol: 110, ISSN: 2470-0010The tilt-to-length coupling during the LISA Pathfinder mission has been numerically and analytically modeled for particular time spans. In this work, we investigate the long-term stability of the coupling coefficients of this noise. We show that they drifted slowly (by 1 μm/rad and 6×10-6 in 100 days) and were strongly correlated to temperature changes within the satellite (8 μm/rad/K and 30×10-6/K). Based on analytical tilt-to-length coupling models, we attribute the temperature-driven coupling changes to rotations of the test masses and small distortions in the optical setup. Particularly, our findings lead to the conclusion that LISA Pathfinder's optical baseplate was bent during the cooldown experiment, which started in late 2016 and lasted several months.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Search for Time-Dependent CP Violation in D^{0}→π^{+}π^{-}π^{0} Decays.
, Phys Rev Lett, Vol: 133A measurement of time-dependent CP violation in D^{0}→π^{+}π^{-}π^{0} decays using a pp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7 fb^{-1}, is presented. The initial flavor of each D^{0} candidate is determined from the charge of the pion produced in the D^{*}(2010)^{+}→D^{0}π^{+} decay. The decay D^{0}→K^{-}π^{+}π^{0} is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CP asymmetry ΔY in D^{0}→π^{+}π^{-}π^{0} decays is measured to be ΔY=(-1.3±6.3±2.4)×10^{-4}, where the first uncertainty is statistical and the second is systematic, which is compatible with CP conservation.
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Journal articleCms Collaboration T, 2024,
Observation ofγγ→ττin proton-proton collisions and limits on the anomalous electromagnetic moments of the τ lepton.
, Rep Prog Phys, Vol: 87The production of a pair of τ leptons via photon-photon fusion,γγ→ττ, is observed for the first time in proton-proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb-1. Events with a pair of τ leptons produced via photon-photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section ofγγ→ττisσobsfid=12.4-3.1+3.8fb. Constraints are set on the contributions to the anomalous magnetic moment (aτ) and electric dipole moments (dτ) of the τ lepton originating from potential effects of new physics on theγττvertex:aτ=0.0009-0.0031+0.0032and|dτ|<2.9×10-17ecm(95% confidence level), consistent with the standard model.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Search for the rare decay of charmed baryon Λc+ into the pμ+μ- final state
, Physical Review D, Vol: 110, ISSN: 2470-0010A search for the nonresonant Λc+→pμ+μ- decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb-1. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λc+→pμ+μ- decay is determined to be 2.9(3.2)×10-8 at 90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the η, ρ and ω resonances are also determined.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Comprehensive analysis of local and nonlocal amplitudes in the B<sup>0</sup>→ K<sup>*0</sup>μ<sup>+</sup>μ<sup>−</sup> decay
, Journal of High Energy Physics, Vol: 2024A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0 → K*0(→ K+π−)μ+μ− is performed by analysing the phase-space distribution of the decay products. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb−1 collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient C9, responsible for vector dimuon currents, exhibits a 2.1σ deviation from the Standard Model expectation. The Wilson Coefficients C10, C9′ and C10′ are all in better agreement than C9 with the Standard Model and the global significance is at the level of 1.5σ. The model used also accounts for nonlocal contributions from B0→ K*0[τ+τ−→ μ+μ−] rescattering, resulting in the first direct measurement of the bsττ vector effective-coupling C9τ.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Performance of the CMS electromagnetic calorimeter in pp collisions at √<inf>s</inf> = 13 TeV
, Journal of Instrumentation, Vol: 19The operation and performance of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) are presented, based on data collected in pp collisions at √s = 13 TeV at the CERN LHC, in the years from 2015 to 2018 (LHC Run 2), corresponding to an integrated luminosity of 151 fb-1. The CMS ECAL is a scintillating lead-tungstate crystal calorimeter, with a silicon strip preshower detector in the forward region that provides precise measurements of the energy and the time-of-arrival of electrons and photons. The successful operation of the ECAL is crucial for a broad range of physics goals, ranging from observing the Higgs boson and measuring its properties, to other standard model measurements and searches for new phenomena. Precise calibration, alignment, and monitoring of the ECAL response are important ingredients to achieve these goals. To face the challenges posed by the higher luminosity, which characterized the operation of the LHC in Run 2, the procedures established during the 2011-2012 run of the LHC have been revisited and new methods have been developed for the energy measurement and for the ECAL calibration. The energy resolution of the calorimeter, for electrons from Z boson decays reaching the ECAL without significant loss of energy by bremsstrahlung, was better than 1.8%, 3.0%, and 4.5% in the |η| intervals [0.0,0.8], [0.8,1.5], [1.5, 2.5], respectively. This resulting performance is similar to that achieved during Run 1 in 2011-2012, in spite of the more severe running conditions.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for a resonance decaying to a W boson and a photon in proton-proton collisions at s = 13 TeV using leptonic W boson decays
, Journal of High Energy Physics, Vol: 2024A search for a new charged particle X with mass between 0.3 and 2.0 TeV decaying to a W boson and a photon is presented, using proton-proton collision data at a center-of-mass energy of 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb−1. Particle X has electric charge ±1 and is assumed to have spin 0. The search is performed using the electron and muon decays of the W boson. No significant excess above the predicted background is observed. The upper limit at 95% confidence level on the product of the production cross section of the X and its branching fraction to a W boson and a photon is found to be 94 (137) fb for a 0.3 TeV resonance and 0.75 (0.81) fb for a 2.0 TeV resonance, for an X width-to-mass ratio of 0.01% (5%). This search presents the most stringent constraints to date on the existence of such resonances across the probed mass range. A statistical combination with an earlier study based on the hadronic decay mode of the W boson is also performed, and the upper limit at 95% confidence level for a 2.0 TeV resonance is reduced to 0.50 (0.63) fb for an X width-to-mass ratio of 0.01% (5%).
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Journal articleAbed Abud A, Abi B, Acciarri R, et al., 2024,
Performance of a Modular Ton-Scale Pixel-Readout Liquid Argon Time Projection Chamber
, Instruments, Vol: 8The Module-0 Demonstrator is a single-phase 600 kg liquid argon time projection chamber operated as a prototype for the DUNE liquid argon near detector. Based on the ArgonCube design concept, Module-0 features a novel 80k-channel pixelated charge readout and advanced high-coverage photon detection system. In this paper, we present an analysis of an eight-day data set consisting of 25 million cosmic ray events collected in the spring of 2021. We use this sample to demonstrate the imaging performance of the charge and light readout systems as well as the signal correlations between the two. We also report argon purity and detector uniformity measurements and provide comparisons to detector simulations.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Performance of CMS muon reconstruction from proton-proton to heavy ion collisions
, Journal of Instrumentation, Vol: 19The performance of muon tracking, identification, triggering, momentum resolution, and momentum scale has been studied with the CMS detector at the LHC using data collected at √s NN= 5.02 TeV in proton-proton (pp) and lead-lead (PbPb) collisions in 2017 and 2018, respectively, and at √s NN= 8.16 TeV in proton-lead (pPb) collisions in 2016. Muon efficiencies, momentum resolutions, and momentum scales are compared by focusing on how the muon reconstruction performance varies from relatively small occupancy pp collisions to the larger occupancies of pPb collisions and, finally, to the highest track multiplicity PbPb collisions. We find the efficiencies of muon tracking, identification, and triggering to be above 90% throughout most of the track multiplicity range. The momentum resolution and scale are unaffected by the detector occupancy. The excellent muon reconstruction of the CMS detector enables precision studies across all available collision systems.
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Journal articleOdagiu P, Que Z, Duarte J, et al., 2024,
Ultrafast jet classification at the HL-LHC
, Machine Learning: Science and Technology, Vol: 5, ISSN: 2632-2153Three machine learning models are used to perform jet origin classification. These models are optimized for deployment on a field-programmable gate array device. In this context, we demonstrate how latency and resource consumption scale with the input size and choice of algorithm. Moreover, the models proposed here are designed to work on the type of data and under the foreseen conditions at the CERN large hadron collider during its high-luminosity phase. Through quantization-aware training and efficient synthetization for a specific field programmable gate array, we show that O(100) ns inference of complex architectures such as Deep Sets and Interaction Networks is feasible at a relatively low computational resource cost.
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Journal articleMcGarrigle JM, Long KR, Prezado Y, 2024,
On the significance of the different geometrical and dosimetric parameters in microbeam and minibeam radiation therapy a retrospective evaluation
, Frontiers in Oncology, Vol: 14, ISSN: 2234-943XIntroduction: Spatially Fractionated Radiation Therapy (SFRT) is an unconventional therapeutic approach with the potential to disrupt the classical paradigms of conventional radiation therapy. The high spatial dose modulation in SFRT is believed to activate distinct radiobiological mechanisms which lead to remarkable increases in normal tissue tolerance. To make optimal use of SFRT and its benefits, a deeper understanding of the biological response and its relationship with the complex dosimetric and geometric components of SFRT is essential.Method: A retrospective evaluation of preclinical studies was conducted to gain insight into the dosimetric and geometric parameters that are most correlated with normal tissue response. Current literature evaluates the response of tissue to MBRT and MRT according to various end points, e.g. the level of desquamation, degree of necrosis, or the amount of malcalcification. A set of metrics was developed to allow a quantitative comparison of these results.Results: The strongest correlations were observed with the doses in both the peaks and valleys as well as the ratio of the area covered by the peak over the total area. This emphasises the geometry of the beam. MBRT challenged previous uniform dose-distribution paradigms by highlighting the critical role of Peak Dose alongside Valley Dose in tissue sparing whereas MRT underscores the significant influence of geometric beam parameters on tissue preservation.Discussion: The data exhibits variability in the results obtained using different animal models and endpoints and additional research is warranted to explore the trends observed in this study under controlled conditions.
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