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Measurement of D0, D+, D+(s) and D*+ Production in Fixed Target 920-GeV Proton-Nucleus Collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C52 (2007) 531-542, 2007.
Inspire Record 757982 DOI 10.17182/hepdata.57312

The inclusive production cross sections of the charmed mesons D^0, D^+, D_s^+ and D^{*+} have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of transverse momentum and Feynman's x variable are given for the central rapidity region and for transverse momenta up to $\pT=3.5$ GeV/$c$. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.

7 data tables

Cross sections (micro barns) in the visible range (-0.15<x_F<0.05).

Cross sections (micro barns) extrapolated to the total phase space.

Cross sections(micro barns) for particles production in the visible range (-0.15<x_F<0.05).

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Bottom production cross-section from double muonic decays of b-flavoured hadrons in 920-GeV proton-nucleus collision

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Phys.Lett. B650 (2007) 103-110, 2007.
Inspire Record 734145 DOI 10.17182/hepdata.57461

The b-bbar production cross section in 920 GeV proton-nucleus fixed target collisions is measured by observing double muonic decays of b-flavored hadrons in the kinematic region $-0.3<\xF(\mu)<0.15$. A total number of $76\pm12$ b-bbar events is obtained with a likelihood fit of the signal and background simulated events to the data. The resulting cross section is $\sigbb = 16.2 \pm 2.5_{stat} \pm 2.8_{sys} \nbpn$, or, when combined with a previous Hera-B measurement of similar precision, $\sigbb = 15.4 \pm 1.7_{stat} \pm 1.2_{sys}^{uncorr.} \pm 1.9_{sys}^{corr.} \nbpn$, which is consistent with recent NLO calculations.

2 data tables

BOTTOM BOTTOMBAR production cross section.

BOTTOM BOTTOMBAR production cross section combined with previous HERA-B measurement.


Kinematic distributions and nuclear effects of J/psi production in 920-GeV fixed-target proton-nucleus collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C60 (2009) 525-542, 2009.
Inspire Record 804247 DOI 10.17182/hepdata.57472

Measurements of the kinematic distributions of $J/\psi$ mesons produced in $p-$C, $p-$Ti and $p-$W collisions at $\sqrt{s}=41.6 \mathrm{GeV}$ in the Feynman-$x$ region $-0.34 < x_{F} < 0.14$ and for transverse momentum up to $p_T = 5.4 \mathrm{GeV}/c$ are presented. The $x_F$ and $p_T$ dependencies of the nuclear suppression parameter, $\alpha$, are also given. The results are based on $2.4 \cdot 10^{5}$ $J/\psi$ mesons in both the $e^+ e^-$ and $\mu^{+}\mu^{-}$ decay channels. The data have been collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The measurement explores the negative region of $x_{F}$ for the first time. The average value of $\alpha$ in the measured $x_{F}$ region is $0.981 \pm 0.015$. The data suggest that the strong nuclear suppression of $J/\psi$ production previously observed at high $x_F$ turns into an enhancement at negative $x_F$.

4 data tables

J/PSI distributions (dN/dp_T, normalized to their integrals over the measured range) for three targets materials with statistical and systematics uncertainties.

J/PSI distributions (dN/dx_F, normalized to their integrals over the measured range) for three targets materials with statistical and systematics uncertainties.

The parameter Alpha as a function of p_T. Statistical and systematic uncertainties are indicated separately.

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Angular distributions of leptons from $J/\psi$ ' $s$ produced in 920 GeV fixed-target proton-nucleus collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C60 (2009) 517-524, 2009.
Inspire Record 810555 DOI 10.17182/hepdata.57473

A study of the angular distributions of leptons from decays of J/psi's produced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed in the Feynman-x region -0.34 < x_F < 0.14 and for transverse momentum up to 5.4 GeV/c. The data were collected by the HERA-B experiment at the HERA proton ring of the DESY laboratory. The results, based on a clean selection of 2.3 x 10^5 J/psi's reconstructed in both the e^+ e^- and mu^+ mu^- decay channels, indicate that J/psi's are produced with longitudinal polarization. The magnitude of the effect is maximal at low p_T. For p_T >1 GeV/c a significant dependence on the reference frame is found: the polar anisotropy is more pronounced in the Collins-Soper frame and almost vanishes in the helicity frame, where, instead, a significant azimuthal anisotropy arises.

9 data tables

Output parameters obtained by fitting the distributions.

Values of the parameters Lambda_theta, Lambda_phi et Lambda_theta_phi measured in the Collins-Soper frame as functions of the average reconstructed p_T for combined carbon and tungsten data.

Values of the parameters Lambda_theta, Lambda_phi et Lambda_theta_phi measured in the Collins-Soper frame as functions of the average reconstructed x_F for combined carbon and tungsten data.

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Production of the Charmonium States $\chi_{c1}$ and $\chi_{c2}$ in Proton Nucleus Interactions at $\sqrt{s}$ = 41.6-GeV

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Phys.Rev. D79 (2009) 012001, 2009.
Inspire Record 790682 DOI 10.17182/hepdata.57464

A measurement of the ratio R_chic = (chic -> Jpsi + gam)/ Jpsi in pC, pTi and pW interactions at 920 GeV/c (sqrt{s}=41.6 GeV) in the Feynman-x range -0.35 < x_F(Jpsi) < 0.15 is presented. Both mu+mu- and e+e- Jpsi decay channels are observed with an overall statistics of about 15000 chic events, which is by far the largest available sample in pA collisions. The result is R_chic = 0.188+-0.013(st)(+0.024)(-0.022)(sys) averaged over the different materials, when no Jpsi and chic polarisations are considered. The chic_1 to chic_2 production ratio R_12 = R_chic1/R_chic2 is measured to be 1.02+-0.40, leading to a cross section ratio sigma(chic_1)/sigma(chic_2)=0.57+-0.23. The dependence of R_chic on the Feynman-x of the Jpsi, x_F(Jpsi), and its transverse momentum, p_T(Jpsi), is studied, as well as its dependence on the atomic number, A, of the target. For the first time, an extensive study of possible biases on R_chic and R_12 due to the dependence of acceptance on the polarization states of Jpsi and chic is performed. By varying the polarisation parameter, lambda(obs), of all produced Jpsi's by two sigma around the value measured by HERA-B, and considering the maximum variation due to the possible chic_1 and chic_2 polarisations, it is shown that R_chic could change by a factor between 1.02 and 1.21 and R_12 by a factor between 0.89 and 1.16.

3 data tables

Measurement of R_CHI/C in <E+ E->, <MU+ MU-> and combined channel.

Measurement of R_12 in <E+ E->, <MU+ MU-> and combined channel.

Measurement of SIG(C1)/SIG(C2) in <E+ E->, <MU+ MU-> and combined channel.


A Measurement of the $\psi^\prime$ to $J/\psi$ production ratio in 920-GeV proton-nucleus interactions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C49 (2007) 545-558, 2007.
Inspire Record 722216 DOI 10.17182/hepdata.57451

Ratios of the Psi' over the J/psi production cross sections in the dilepton channel for C, Ti and W targets have been measured in 920 GeV proton-nucleus interactions with the HERA-B detector at the HERA storage ring. The Psi' and J/psi states were reconstructed in both the mu+mu- and the e+e- decay modes. The measurements covered the kinematic range -0.35 < x_F < 0.1 with transverse momentum p_T < 4.5 GeV/c. The Psi' to J/psi production ratio is almost constant in the covered x_F range and shows a slow increase with p_T. The angular dependence of the ratio has been used to measure the difference of the Psi' and J/psi polarization. All results for the muon and electron decay channels are in good agreement: their ratio, averaged over all events, is R_psi'(mu)/R_psi'(e)=1.00+-0.08+-0.04. This result constitutes a new, direct experimental constraint on the double ratio of branching fractions, (B'(mu)*B(e))/(B(mu)*B'(e)), of Psi' and J/psi in the two channels.

3 data tables

Ratio of PSI(3685) and J/PSI cross sections for both muon and electron channels combined, obtained for different cos theta in the s-channel helicity frame.

Ratio of PSI(3685) and J/PSI cross sections for both muon and electron channels combined, obtained for intervals inpT using the data from all targets.

Ratio of PSI(3685) and J/PSI production cross sections per nucleus.


Search for the flavor changing neutral current decay D0 ---> mu+ mu- with the HERA-B detector

The HERA-B collaboration Abt, I. ; Adams, M. ; Albrecht, H. ; et al.
Phys.Lett. B596 (2004) 173-183, 2004.
Inspire Record 650658 DOI 10.17182/hepdata.57496

We report on a search for the flavor-changing neutral current decay $D^0 \to \mu^+\mu^-$ using $50 \times 10^6$ events recorded with a dimuon trigger in interactions of 920 GeV protons with nuclei by the HERA-B experiment. We find no evidence for such decays and set a 90% confidence level upper limit on the branching fraction $Br(D^0 \to \mu^+\mu^-) &lt;2.0 \times 10^{-6}$.

1 data table

Upper limit on the branching fraction of D0 --> MU+ MU- in P NUCLEON interaction.


$J/\psi$ production via chi($c$) decays in 920-GeV pA interactions

The HERA-B collaboration Abt, I. ; Abyzov, A. ; Adams, M. ; et al.
Phys.Lett. B561 (2003) 61-72, 2003.
Inspire Record 601830 DOI 10.17182/hepdata.57487

Using data collected by the HERA-B experiment, we have measured the fraction of J\psi's produced via radiative chi_c decays in interactions of 920 GeV protons with carbon and titanium targets. We obtained R_{\chi_c} = 0.32 \pm 0.06_{stat} \pm 0.04_{sys} for the fraction of J\psi from chi_c decays averaged over proton-carbon and proton-titanium collisions. This result is in agreement with previous measurements and is compared with theoretical predictions.

4 data tables

Ratio of CHIC to J/PSI production cross section in P C interactions for the E+ E- and MU+ MU- channels separately.

Ratio of CHI/C to J/PSI production cross section in P TI interactions for the E+ E- and MU+ MU- channels separately.

Averaged ratio of CHIC to J/PSI production cross section in P C and P Ti interactions.

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Measurement of the $\upsilon$ production cross-section in 920-GeV fixed-target proton-nucleus collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Phys.Lett. B638 (2006) 13-21, 2006.
Inspire Record 711926 DOI 10.17182/hepdata.57495

The proton-nucleon cross section ratio $R=Br(\Upsilon\to l^+l^-) d\sigma(\Upsilon)/dy|_{y=0} / {\sigma(J/\psi)}$ has been measured with the HERA-B spectrometer in fixed-target proton-nucleus collisions at 920 GeV proton beam energy corresponding to a proton-nucleon cms energy of sqrt{s}=41.6 GeV. The combined results for the Upsilon decay channels Upsilon $\to e^+e^-$ and Upsilon $\to\mu^+\mu^-$ yield a ratio $R=(9.0 \pm 2.1) 10^{-6}$. The corresponding Upsilon production cross section per nucleon at mid-rapidity (y=0) has been determined to be $Br(\Upsilon\to{}l^+l^-) {d\sigma(\Upsilon)/dy}|_{y=0}= 4.5 \pm 1.1 $ pb/nucleon.

2 data tables

Ratio of the UPSILON production cross section to the total J/PSI production cross section in P NUCLEON interactions for the E+ E- and MU+ MU- channels separately and combined. The total uncertainty is indicated for the combined results.

UPSILON production cross section at midrapidity in P NUCLEON interactions for the E+ E- and MU+ MU- channels separately and combined. The total uncertainty is indicated for the combined results.


V0 production in p+A collisions at s**(1/2) = 41.6-GeV

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C61 (2009) 207-221, 2009.
Inspire Record 810078 DOI 10.17182/hepdata.52478

Inclusive doubly differential cross sections d^2\sigma_{pA}/dx_Fdp_T^2 as a function of Feynman-x (x_F) and transverse momentum (p_T) for the production of K^0_s, Lambda^0 and anti-Lambda^0 in proton-nucleus interactions at 920 GeV are presented. The measurements were performed by HERA-B in the negative x_F range (-0.12<x_F<0.0) and for transverse momenta up to p_T= 1.6 GeV/c. Results for three target materials: carbon, titanium and tungsten are given. The ratios of production cross sections are presented and discussed. The Cronin effect is clearly observed for all three V^0 species. The atomic number dependence is parameterized as \sigma_{pA} = \sigma_{pN} \cdot A^\alpha where \sigma_{pN} is the proton-nucleon cross section. The measured values of \alpha are all near one. The results are compared with EPOS 1.67 and PYTHIA 6.3. EPOS reproduces the data to within \approx 20% except at very low transverse momentum.

12 data tables

Visible cross sections for K0S production in acceptance of the measurement.

Visible cross sections for K0S production in acceptance of the measurement.

Visible cross sections for K0S production in acceptance of the measurement.

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K*0 and phi meson production in proton-nucleus interactions at s**(1/2) = 41.6-GeV

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Eur.Phys.J. C50 (2007) 315-328, 2007.
Inspire Record 719788 DOI 10.17182/hepdata.43089

The inclusive production cross sections of the strange vector mesons K*0, K*0bar, and phi have been measured in interactions of 920 GeV protons with C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of rapidity and transverse momentum have been measured in the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic number dependence is parametrised as sigma(pA) = sigma(pN)*A**alpha, where sigma(pN) is the proton-nucleon cross section. Within the phase space accessible, alpha(K*0) = 0.86+/-0.03, alpha(K*0bar) = 0.87+/-0.03, and alpha(phi) = 0.96+/-0.02. The total proton-nucleon cross sections, determined by extrapolating the differential measurements to full phase space, are sigma(pN->K*0) = 5.06+/-0.54 mb, sigma(pN->K*0bar) = 4.02+/-0.45 mb, and sigma(pN->phi) = 1.17+/-0.11 mb. The Cronin effect is observed for the first time for vector mesons containing strange quarks/ compared to the measurements of Cronin et al. for K+- mesons, the measured values of alpha for phi mesons coincide with those of K- mesons for all transverse momenta, while the enhancement for K*0 / K*0bar mesons is smaller.

13 data tables

Measured rapidity distribution for K*0 production in the accessible phase space.

Measured rapidity distribution for K*BAR0 production in the accessible phase space.

Measured rapidity distribution for PHI production in the accessible phase space.

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Improved measurement of the b-anti-b production cross section in 920-GeV fixed-target proton-nucleus collisions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Phys.Rev. D73 (2006) 052005, 2006.
Inspire Record 700310 DOI 10.17182/hepdata.57501

A new measurement of the b-bbar production cross section in 920 GeV proton-nucleus collisions is presented by the HERA-B collaboration. The b-bbar production is tagged via inclusive bottom quark decays into J/psi mesons, by exploiting the longitudinal separation of J/psi->ll decay vertices from the primary proton-nucleus interaction point. Both e+e- and mu+mu- channels are reconstructed, for a total of 83 +- 12 inclusive b->J/psi X events found. The combined analysis yields a b-bbar to prompt J/psi cross section ratio of ${\frac{{\Delta\sigma(bbbar)}}{{\Delta\sigma_{\jpsi}}}} = 0.032\pm 0.005 \stat \pm 0.004 \sys$ measured in the x_f acceptance (-0.35 <x_f <0.15), extrapolated to $\sigma(bbbar) = 14.9 \pm 2.2 \stat \pm 2.4 \sys $ nb/nucleon in the total phase space.

7 data tables

Ratio of prompt J/PSI to B-BBAR production cross section in P C interactions in the Feynmann X range -0.35 to 0.15 for the E+ E- and MU+ MU- channels separately and combined.

Ratio of prompt J/PSI to B-BBAR production cross section in P TI interactions in the Feynmann X range -0.35 to 0.15 for the E+ E- and MU+ MU- channels separately and combined.

Ratio of prompt J/PSI to B-BBAR production cross section in P WT interactions in the Feynmann X range -0.35 to 0.15 for the E+ E- and MU+ MU- channels separately and combined.

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Measurement of the $J/\psi$ production cross section in 920-GeV/c fixed-target proton-nucleus interactions

The HERA-B collaboration Abt, I. ; Adams, M. ; Agari, M. ; et al.
Phys.Lett. B638 (2006) 407-414, 2006.
Inspire Record 700309 DOI 10.17182/hepdata.57500

The mid-rapidity (dsigma_(pN)/dy at y=0) and total sigma_(pN) production cross sections of J/Psi mesons are measured in proton-nucleus interactions. Data collected by the HERA-B experiment in interactions of 920 GeV/c protons with carbon, titanium and tungsten targets are used for this analysis. The J/Psi mesons are reconstructed by their decay into lepton pairs. The total production cross section obtained is sigma_(pN)(J/Psi) = 663 +- 74 +- 46 nb/nucleon. In addition, our result is compared with previous measurements.

4 data tables

Cross section for the individual targets for the visible rapidity region.

Total cross section for the individual targets extrapolated to the full phase space.

Total cross section for P NUCLEON --> J/PSI X for the full phase space.

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Inclusive V0 production cross-sections from 920-GeV fixed target proton nucleus collisions

The HERA-B collaboration Abt, I. ; Abyzov, A. ; Adams, M. ; et al.
Eur.Phys.J. C29 (2003) 181-190, 2003.
Inspire Record 604661 DOI 10.17182/hepdata.46479

Inclusive differential cross sections $d\sigma_{pA}/dx_F$ and $d\sigma_{pA}/dp_t^2$ for the production of \kzeros, \lambdazero, and \antilambda particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to $\sqrt {s} = 41.6$ GeV in the proton-nucleon system. The ratios of differential cross sections \rklpa and \rllpa are measured to be $6.2\pm 0.5$ and $0.66\pm 0.07$, respectively, for \xf $\approx-0.06$. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions $d\sigma_{pA}/dp_t^2$ also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections $\sigma_{pA}$ on the atomic mass $A$ of the target material is discussed, and the deduced cross sections per nucleon $\sigma_{pN}$ are compared with results obtained at other energies.

7 data tables

Inclusive differential cross section DSIG/DXL for K0S production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.

Inclusive differential cross section DSIG/DXL for LAMBDA production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to thefull XL range.

Inclusive differential cross section DSIG/DXL for LAMBDABAR production in the XL interval -0.12 to 0.0 plus the total cross section after extrapolation to the full XL range.

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Measurement of the b anti-b production cross-section in 920-GeV fixed target proton nucleus collisions

The HERA-B collaboration Abt, I. ; Abyzov, A. ; Adams, M. ; et al.
Eur.Phys.J. C26 (2003) 345-355, 2003.
Inspire Record 587753 DOI 10.17182/hepdata.57488

Using the HERA-B detector, the b-bbar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b-bbar production was tagged via inclusive bottom quark decays into J/psi, by exploiting the longitudinal separation of J/psi->ll decay vertices from the primary proton-nucleus interaction. Both $e^+e^-$ and $\mu^+\mu^-$ channels have been reconstructed and the combined analysis yields the cross section $\sigma(b \bar b) = 32 ^{+14}_{-12} (stat) ^{+6}_{-7} (sys) nb/nucleon$.

2 data tables

The measured cross section for the E+ E- and MU+ MU- channels separately.

The measured and extrapolated combined B-BBAR production cross section.