We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at sqrts=13.6 TeV collected by SND@LHC in ...2022 is used, corresponding to an integrated luminosity of 36.8 fb^{-1}. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2<η<8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ν_{μ} interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ν_{μ} signal.
Many scenarios of physics beyond the standard model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional ...scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an e+e− collider, such a leptophilic scalar (ϕL) would be produced predominantly through radiation from a τ lepton. We report herein a search for e+e−→τ+τ−ϕL, ϕL→ℓ+ℓ− (ℓ=e, μ) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the ϕL coupling to leptons in the range 0.04<mϕL<7.0 GeV. These bounds significantly improve upon the current constraints, excluding almost entirely the parameter space favored by the observed discrepancy in the muon anomalous magnetic moment below 4 GeV at 90% confidence level.
We study the process e + e − → e + e − η ′ in the double-tag mode and measure for the first time the γ * γ * → η ′ transition form factor F η′ ( Q 2 1 , Q 2 2 ) in the momentum-transfer range 2 < Q 2 ...1 , Q 2 2 < 60 GeV 2 . The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb − 1 collected at the PEP-II e + e − collider with the BABAR detector at center-of-mass energies near 10.6 GeV.
We present a program to calculate the total cross section for top-quark pair production in hadronic collisions. The program takes into account recent theoretical developments such as approximate ...next-to-next-to-leading order perturbative QCD corrections and it allows for studies of the theoretical uncertainty by separate variations of the factorization and renormalization scales. In addition it offers the possibility to obtain the cross section as a function of the running top-quark mass. The program can also be applied to a hypothetical fourth quark family provided the QCD couplings are standard.
Program title: Hathor
Catalogue identifier: AEID_v1_0
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/AEID_v1_0.html
Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland
Licensing provisions: GNU GPL 3
No. of lines in distributed program, including test data, etc.: 5405
No. of bytes in distributed program, including test data, etc.: 327 718
Distribution format: tar.gz
Programming language: C++, Fortran, Java
Computer: Standard PCs (x86, x86_64 processors)
Operating system: Linux
RAM: 256 MB
Classification: 11.1
External routines: Interface to LHAPDF for the user's choice of parton distribution functions, see
http://projects.hepforge.org/lhapdf/
Nature of problem: Computation of total cross section in perturbative QCD.
Solution method: Numerical integration of hard parton cross section convoluted with parton distribution functions.
Running time: A few seconds to a few minutes on standard desktop PCs or notebooks, depending on the chosen options.
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