Results of the HARP experiment Part 2 I.Boyko, Yu.Nefedov

Particle identification π+π+ π-π- p

The HARP split At the begin of the data analysis, HARP broke into two parts over a deep split of opinion on quality of work, working methods, and professional ethics. –'HARP Collaboration' or 'Official HARP' (OH) –'HARP-CDP group' (CERN, Dubna, Protvino) In this seminar, we represent HARP-CDP Between OH and HARP-CDP, only the raw data and the computing infrastructure are common. The analysis strategies and software are totally independent.

The “500 ps effect” Citation from 2008 JINST 3 P04007: `The remaining difference observed … is of the order of (150±100) ps at 450 MeV/c’

ΔT = = (350±40)ps 480±30 ps 130±20 ps Δt (ns)

What is wrong with OH calibration Momentum bias Δ(1/P T ) = 0.3 (c/GeV) Poor momentum resolution σ(1/P T ) = (c/GeV) –CDP: (c/GeV) TOF resolution: σ(TOF) = 305 ps –CDP: σ(TOF) = 175 ps Unphysical “500 ps effect” in RPC

Comparison of GEANT4 hadronic models with the HARP-CDP data

GEANT4 (LHEP) angular spectrum of π + produced by 8.9 GeV protons

GEANT4 versus HARP-CDP data

The “LSND puzzle”

On the “LSND puzzle” LSND: anomalous 4 σ signal of anti- ν e from the interactions of E kin =800 MeV protons in water. LSND interpretation: –anti- ν μ → anti - ν e oscillations –with Δm 2 ~ 1 eV 2 Sterile neutrinos? MiniBooNe disagrees with LSND Question: is π - / π + ratio correct? π+π+ π-π- μ+μ+ νμνμ μ-μ- _νμ_νμ _νe_νe νμνμ e-e- e+e+ _νμ_νμ νeνe p+H 2 O

π - / π + ratio: LSND vs HARP-CDP LSND parametrization

Production of hadrons by +8.9 GeV/c and -8.0 GeV/c proton and pion beams on 5% λ Be target

What we measure p π+π+ π- π- K+d p π+π+ π-π- - Secondary particle Beam

Some cross-section plots Positive pion beamNegative pion beam

Comparison with OH

Comparison with E910 E910: 1.5 m long flat-geometry TPC

HARP-CDP is going to publish lots of precise cross- sections of hadron production on nuclei. 'Official HARP' publish cross-sections that are wrong by factors up to two (to our regret, with participation of JINR Dubna authors). 'Official HARP' consciously ignore: –the conclusions of the CERN/INFN Review Board for HARP (chairman L. Foa): '...The RBH finds clear evidence for a significant momentum bias in the OH analysis...the RBH finds no evidence if any significant momentum bias in the CDP analysis...' –the conclusions of the CERN-SPSC Review (chairman J. Dainton): '...This calls into question the validity of the results in recent publications by the HARP collaboration of their large angle data, based on analysis (a)[=OH]...‘ –our published calibration work of the TPC and the RPCs

Backup slide