131 research outputs found
Precise Measurement of the Neutrino Mixing Parameter theta(23) from Muon Neutrino Disappearance in an Off-Axis Beam
New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter theta_{23}. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57 x 10^{20} protons on target, T2K has fit the energy-dependent nu_mu oscillation probability to determine oscillation parameters. Marginalizing over the values of other oscillation parameters yields sin^2 (theta_{23}) = 0.514 +0.055/-0.056 (0.511 +- 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Delta m^2_{32} = (2.51 +- 0.10) x 10^{-3} eV^2/c^4 (inverted hierarchy: Delta m^2_{13} = (2.48 +- 0.10) x 10^{-3} eV^2/c^4). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty
Measurement of the intrinsic electron neutrino component in the T2K neutrino beam with the ND280 detector
The T2K experiment has reported the first observation of the appearance of electron neutrinos in a muon neutrino beam. The main and irreducible background to the appearance signal comes from the presence in the neutrino beam of a small intrinsic component of electron neutrinos originating from muon and kaon decays. In T2K, this component is expected to represent 1.2% of the total neutrino flux. A measurement of this component using the near detector (ND280), located 280 m from the target, is presented. The charged current interactions of electron neutrinos are selected by combining the particle identification capabilities of both the time projection chambers and electromagnetic calorimeters of ND280. The measured ratio between the observed electron neutrino beam component and the prediction is 1.01 +/- 0.10 providing a direct confirmation of the neutrino fluxes and neutrino cross section modeling used for T2K neutrino oscillation analyses. Electron neutrinos coming from muons and kaons decay are also separately measured, resulting in a ratio with respect to the prediction of 0.68 +/- 0.30 and 1.10 +/- 0.14, respectively
Studies of and production in and Pb collisions
The production of and mesons is studied in proton-proton and
proton-lead collisions collected with the LHCb detector. Proton-proton
collisions are studied at center-of-mass energies of and ,
and proton-lead collisions are studied at a center-of-mass energy per nucleon
of . The studies are performed in center-of-mass rapidity
regions (forward rapidity) and
(backward rapidity) defined relative to the proton beam direction. The
and production cross sections are measured differentially as a function
of transverse momentum for and , respectively. The differential cross sections are used to
calculate nuclear modification factors. The nuclear modification factors for
and mesons agree at both forward and backward rapidity, showing
no significant evidence of mass dependence. The differential cross sections of
mesons are also used to calculate cross section ratios,
which show evidence of a deviation from the world average. These studies offer
new constraints on mass-dependent nuclear effects in heavy-ion collisions, as
well as and meson fragmentation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb
public pages
T2K neutrino flux prediction
cited By 15 art_number: 012001 affiliation: Centre for Particle Physics, Department of Physics, University of Alberta, Edmonton, AB, Canada; Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics (LHEP), University of Bern, Bern, Switzerland; Department of Physics, Boston University, Boston, MA, United States; Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada; Department of Physics and Astronomy, University of California Irvine, Irvine, CA, United States; IRFU, CEA Saclay, Gif-sur-Yvette, France; Institute for Universe and Elementary Particles, Chonnam National University, Gwangju, South Korea; Department of Physics, University of Colorado at Boulder, Boulder, CO, United States; Department of Physics, Colorado State University, Fort Collins, CO, United States; Department of Physics, Dongshin University, Naju, South Korea; Department of Physics, Duke University, Durham, NC, United States; IN2P3-CNRS, Laboratoire Leprince-Ringuet, Ecole Polytechnique, Palaiseau, France; Institute for Particle Physics, ETH Zurich, Zurich, Switzerland; Section de Physique, DPNC, University of Geneva, Geneva, Switzerland; H. Niewodniczanski Institute of Nuclear Physics PAN, Cracow, Poland; High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan; Institut de Fisica d’Altes Energies (IFAE), Bellaterra (Barcelona), Spain; IFIC (CSIC and University of Valencia), Valencia, Spain; Department of Physics, Imperial College London, London, United Kingdom; INFN Sezione di Bari, Dipartimento Interuniversitario di Fisica, Università e Politecnico di Bari, Bari, Italy; INFN Sezione di Napoli and Dipartimento di Fisica, Università di Napoli, Napoli, Italy; INFN Sezione di Padova, Dipartimento di Fisica, Università di Padova, Padova, Italy; INFN Sezione di Roma, Università di Roma la Sapienza, Roma, Italy; Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russian Federation; Kobe University, Kobe, Japan; Department of Physics, Kyoto University, Kyoto, Japan; Physics Department, Lancaster University, Lancaster, United Kingdom; Department of Physics, University of Liverpool, Liverpool, United Kingdom; Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, United States; Université de Lyon, Université Claude Bernard Lyon 1, IPN Lyon (IN2P3), Villeurbanne, France; Department of Physics, Miyagi University of Education, Sendai, Japan; National Centre for Nuclear Research, Warsaw, Poland; State University of New York at Stony Brook, Stony Brook, NY, United States; Department of Physics and Astronomy, Osaka City University, Department of Physics, Osaka, Japan; Department of Physics, Oxford University, Oxford, United Kingdom; UPMC, Université Paris Diderot, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Paris, France; Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, United States; School of Physics, Queen Mary University of London, London, United Kingdom; Department of Physics, University of Regina, Regina, SK, Canada; Department of Physics and Astronomy, University of Rochester, Rochester, NY, United States; III. Physikalisches Institut, RWTH Aachen University, Aachen, Germany; Department of Physics and Astronomy, Seoul National University, Seoul, South Korea; Department of Physics and Astronomy, University of Sheffield, Sheffield, United Kingdom; University of Silesia, Institute of Physics, Katowice, Poland; STFC, Rutherford Appleton Laboratory, Harwell Oxford, Warrington, United Kingdom; Department of Physics, University of Tokyo, Tokyo, Japan; Institute for Cosmic Ray Research, Kamioka Observatory, University of Tokyo, Kamioka, Japan; Institute for Cosmic Ray Research, Research Center for Cosmic Neutrinos, University of Tokyo, Kashiwa, Japan; Department of Physics, University of Toronto, Toronto, ON, Canada; TRIUMF, Vancouver, BC, Canada; Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada; Faculty of Physics, University of Warsaw, Warsaw, Poland; Institute of Radioelectronics, Warsaw University of Technology, Warsaw, Poland; Department of Physics, University of Warwick, Coventry, United Kingdom; Department of Physics, University of Washington, Seattle, WA, United States; Department of Physics, University of Winnipeg, Winnipeg, MB, Canada; Faculty of Physics and Astronomy, Wroclaw University, Wroclaw, Poland; Department of Physics and Astronomy, York University, Toronto, ON, Canada references: Astier, P., (2003) Nucl. Instrum. Methods Phys. Res., Sect. A, 515, p. 800. , (NOMAD Collaboration), NIMAER 0168-9002 10.1016/j.nima.2003.07.054; Ahn, M., (2006) Phys. Rev. D, 74, p. 072003. , (K2K Collaboration), PRVDAQ 1550-7998 10.1103/PhysRevD.74.072003; Adamson, P., (2008) Phys. Rev. D, 77, p. 072002. , (MINOS Collaboration), PRVDAQ 1550-7998 10.1103/PhysRevD.77.072002; Aguilar-Arevalo, A., (2009) Phys. Rev. D, 79, p. 072002. , (MiniBooNE Collaboration), PRVDAQ 1550-7998 10.1103/PhysRevD.79.072002; (2003) Letter of Intent: Neutrino Oscillation Experiment at JHF, , http://neutrino.kek.jp/jhfnu/loi/loi_JHFcor.pdf, T2K Collaboration; Abe, K., (2011) Nucl. Instrum. Methods Phys. Res., Sect. A, 659, p. 106. , (T2K Collaboration), NIMAER 0168-9002 10.1016/j.nima.2011.06.067; Abe, K., (2011) Phys. Rev. Lett., 107, p. 041801. , (T2K Collaboration), PRLTAO 0031-9007 10.1103/PhysRevLett.107.041801; Abe, K., (2012) Phys. Rev. D, 85, p. 031103. , (T2K Collaboration), PRVDAQ 1550-7998 10.1103/PhysRevD.85.031103; Fukuda, Y., (2003) Nucl. Instrum. Methods Phys. Res., Sect. A, 501, p. 418. , NIMAER 0168-9002 10.1016/S0168-9002(03)00425-X; Beavis, D., Carroll, A., Chiang, I., (1995), Physics Design Report, BNL 52459Abgrall, N., (2011) Phys. Rev. C, 84, p. 034604. , (NA61/SHINE Collaboration), PRVCAN 0556-2813 10.1103/PhysRevC.84.034604; Abgrall, N., (2012) Phys. Rev. C, 85, p. 035210. , (NA61/SHINE Collaboration), PRVCAN 0556-2813 10.1103/PhysRevC.85.035210; Bhadra, S., (2013) Nucl. Instrum. Methods Phys. Res., Sect. A, 703, p. 45. , NIMAER 0168-9002 10.1016/j.nima.2012.11.044; Van Der Meer, S., Report No. CERN-61-07Palmer, R., Report No. CERN-65-32, 141Ichikawa, A., (2012) Nucl. Instrum. Methods Phys. Res., Sect. A, 690, p. 27. , NIMAER 0168-9002 10.1016/j.nima.2012.06.045; Matsuoka, K., (2010) Nucl. Instrum. Methods Phys. Res., Sect. A, 624, p. 591. , NIMAER 0168-9002 10.1016/j.nima.2010.09.074; Abe, K., (2012) Nucl. Instrum. Methods Phys. Res., Sect. A, 694, p. 211. , (T2K Collaboration), NIMAER 0168-9002 10.1016/j.nima.2012.03.023; Abgrall, N., (2011) Nucl. Instrum. Methods Phys. Res., Sect. A, 637, p. 25. , (T2K ND280 TPC Collaboration), NIMAER 0168-9002 10.1016/j.nima.2011.02. 036; Amaudruz, P.-A., (2012) Nucl. Instrum. Methods Phys. Res., Sect. A, 696, p. 1. , (T2K ND280 FGD Collaboration), NIMAER 0168-9002 10.1016/j.nima.2012.08. 020; Battistoni, G., Cerutti, F., Fasso, A., Ferrari, A., Muraro, S., Ranft, J., Roesler, S., Sala, P.R., (2007) AIP Conf. Proc., 896, p. 31. , APCPCS 0094-243X 10.1063/1.2720455; A. Ferrari, P. R. Sala, A. Fasso, and J. Ranft, Report No. CERN-2005-010A. Ferrari P. R. Sala A. Fasso J. Ranft Report No. SLAC-R-773A. Ferrari P. R. Sala A. Fasso J. Ranft Report No. INFN-TC-05-11R. Brun, F. Carminati, and S. Giani, Report No. CERN-W5013Zeitnitz, C., Gabriel, T.A., (1993) Proceedings of International Conference on Calorimetry in High Energy Physics, , in Elsevier Science B.V., Tallahassee, FL; Fasso, A., Ferrari, A., Ranft, J., Sala, P.R., Proceedings of the International Conference on Calorimetry in High Energy Physics, 1994, , in; Beringer, J., (2012) Phys. Rev. D, 86, p. 010001. , (Particle Data Group), PRVDAQ 1550-7998 10.1103/PhysRevD.86.010001; Eichten, T., (1972) Nucl. Phys. B, 44, p. 333. , NUPBBO 0550-3213 10.1016/0550-3213(72)90120-4; Allaby, J.V., Tech. Rep. 70-12 (CERN, 1970)Chemakin, I., (2008) Phys. Rev. C, 77, p. 015209. , PRVCAN 0556-2813 10.1103/PhysRevC.77.015209; Abrams, R.J., Cool, R., Giacomelli, G., Kycia, T., Leontic, B., Li, K., Michael, D., (1970) Phys. Rev. D, 1, p. 1917. , PRVDAQ 0556-2821 10.1103/PhysRevD.1.1917; Allaby, J.V., (1970) Yad. Fiz., 12, p. 538. , IDFZA7 0044-0027; Allaby, J.V., (1969) Phys. Lett. B, 30, p. 500. , PYLBAJ 0370-2693 10.1016/0370-2693(69)90184-1; Allardyce, B.W., (1973) Nucl. Phys. A, 209, p. 1. , NUPABL 0375-9474 10.1016/0375-9474(73)90049-3; Bellettini, G., Cocconi, G., Diddens, A.N., Lillethun, E., Matthiae, G., Scanlon, J.P., Wetherell, A.M., (1966) Nucl. Phys., 79, p. 609. , NUPHA7 0029-5582 10.1016/0029-5582(66)90267-7; Bobchenko, B.M., (1979) Sov. J. Nucl. Phys., 30, p. 805. , SJNCAS 0038-5506; Carroll, A.S., (1979) Phys. Lett. B, 80, p. 319. , PYLBAJ 0370-2693 10.1016/0370-2693(79)90226-0; Cronin, J.W., Cool, R., Abashian, A., (1957) Phys. Rev., 107, p. 1121. , PHRVAO 0031-899X 10.1103/PhysRev.107.1121; Chen, F.F., Leavitt, C., Shapiro, A., (1955) Phys. Rev., 99, p. 857. , PHRVAO 0031-899X 10.1103/PhysRev.99.857; Denisov, S.P., Donskov, S.V., Gorin, Yu.P., Krasnokutsky, R.N., Petrukhin, A.I., Prokoshkin, Yu.D., Stoyanova, D.A., (1973) Nucl. Phys. B, 61, p. 62. , NUPBBO 0550-3213 10.1016/0550-3213(73)90351-9; Longo, M.J., Moyer, B.J., (1962) Phys. Rev., 125, p. 701. , PHRVAO 0031-899X 10.1103/PhysRev.125.701; Vlasov, A.V., (1978) Sov. J. Nucl. Phys., 27, p. 222. , SJNCAS 0038-5506; Feynman, R., (1969) Phys. Rev. Lett., 23, p. 1415. , PRLTAO 0031-9007 10.1103/PhysRevLett.23.1415; Bonesini, M., Marchionni, A., Pietropaolo, F., Tabarelli De Fatis, T., (2001) Eur. Phys. J. C, 20, p. 13. , EPCFFB 1434-6044 10.1007/s100520100656; Barton, D.S., (1983) Phys. Rev. D, 27, p. 2580. , PRVDAQ 0556-2821 10.1103/PhysRevD.27.2580; Skubic, P., (1978) Phys. Rev. D, 18, p. 3115. , PRVDAQ 0556-2821 10.1103/PhysRevD.18.3115; Feynman, R.P., (1972) Photon-Hadron Interactions, , Benjamin, New York; Bjorken, J.D., Paschos, E.A., (1969) Phys. Rev., 185, p. 1975. , PHRVAO 0031-899X 10.1103/PhysRev.185.1975; Taylor, F.E., Carey, D., Johnson, J., Kammerud, R., Ritchie, D., Roberts, A., Sauer, J., Walker, J., (1976) Phys. Rev. D, 14, p. 1217. , PRVDAQ 0556-2821 10.1103/PhysRevD.14.1217; Abgrall, N., (2013) Nucl. Instrum. Methods Phys. Res., Sect. A, 701, p. 99. , NIMAER 0168-9002 10.1016/j.nima.2012.10.079; Hayato, Y., (2002) Nucl. Phys. B, Proc. Suppl., 112, p. 171. , NPBSE7 0920-5632 10.1016/S0920-5632(02)01759-0 correspondence_address1: Abe, K.; Institute for Cosmic Ray Research, Kamioka Observatory, University of Tokyo, Kamioka, Japan coden: PRVDA abbrev_source_title: Phys Rev D Part Fields Gravit Cosmol document_type: Article source: Scopu
Fraction of decays in prompt production measured in pPb collisions at TeV
The fraction of and decays in the prompt
yield, , is measured by
the LHCb detector in pPb collisions at TeV. The study
covers the forward () and backward () rapidity
regions, where is the rapidity in the nucleon-nucleon
center-of-mass system. Forward and backward rapidity samples correspond to
integrated luminosities of 13.6 0.3 nb and 20.8 0.5
nb, respectively. The result is presented as a function of the
transverse momentum in the range 1 GeV/.
The fraction at forward rapidity is compatible with the LHCb
measurement performed in collisions at TeV, whereas the
result at backward rapidity is 2.4 larger than in the forward region
for GeV/. The increase of at low at backward rapidity is compatible with the suppression of the
(2S) contribution to the prompt yield. The lack of in-medium
dissociation of states observed in this study sets an upper limit of
180 MeV on the free energy available in these pPb collisions to dissociate or
inhibit charmonium state formation.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-028.html (LHCb
public pages
Enhanced production of baryons in high-multiplicity collisions at TeV
The production rate of baryons relative to mesons
in collisions at a center-of-mass energy TeV is measured
by the LHCb experiment. The ratio of to production
cross-sections shows a significant dependence on both the transverse momentum
and the measured charged-particle multiplicity. At low multiplicity, the ratio
measured at LHCb is consistent with the value measured in
collisions, and increases by a factor of with increasing multiplicity.
At relatively low transverse momentum, the ratio of to
cross-sections is higher than what is measured in
collisions, but converges with the ratio as the momentum
increases. These results imply that the evolution of heavy quarks into
final-state hadrons is influenced by the density of the hadronic environment
produced in the collision. Comparisons with a statistical hadronization model
and implications for the mechanisms enforcing quark confinement are discussed.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-027.html (LHCb
public pages
A measurement of
Using a dataset corresponding to of integrated
luminosity collected with the LHCb detector between 2011 and 2018 in
proton-proton collisions, the decay-time distributions of the decay modes
and
are studied. The decay-width difference between the light and heavy mass
eigenstates of the meson is measured to be , where the first uncertainty is
statistical and the second systematic.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-025.htm
Helium identification with LHCb
The identification of helium nuclei at LHCb is achieved using a method based
on measurements of ionisation losses in the silicon sensors and timing
measurements in the Outer Tracker drift tubes. The background from photon
conversions is reduced using the RICH detectors and an isolation requirement.
The method is developed using collision data at
recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an
integrated luminosity of . A total of around helium
and antihelium candidates are identified with negligible background
contamination. The helium identification efficiency is estimated to be
approximately with a corresponding background rejection rate of up to
. These results demonstrate the feasibility of a rich
programme of measurements of QCD and astrophysics interest involving light
nuclei.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-DP-2023-002.html (LHCb public
pages
Measurement of the nu(mu) charged-current quasielastic cross section on carbon with the ND280 detector at T2K
This paper reports a measurement by the T2K experiment of the νμ charged current quasielastic (CCQE) cross section on a carbon target with the off-axis detector based on the observed distribution of muon momentum (pμ) and angle with respect to the incident neutrino beam (θμ). The flux-integrated CCQE cross section was measured to be ⟨σ⟩=(0.83±0.12)×10−38 cm2. The energy dependence of the CCQE cross section is also reported. The axial mass, MQEA, of the dipole axial form factor was extracted assuming the Smith-Moniz CCQE model with a relativistic Fermi gas nuclear model. Using the absolute (shape-only) pμ−cosθμ distribution, the effective MQEA parameter was measured to be 1.26+0.21−0.18 GeV/c2 (1.43+0.28−0.22 GeV/c2)
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