rho^0 Photoproduction in Ultra-Peripheral Relativistic Heavy Ion Collisions with STAR
B.I. Abelev et al., Phys. Rev. C 77, 34910 (2008).

Fig 2a. ZDC east spectra obtained with the minimum bias sample after the rho^0 selection cuts are applied.

Energy deposit (arb. units) Entries (arb. units)
2 0 +- 0
6 1 +- 1
10 40 +- 6.32456
14 174 +- 13.1909
18 305 +- 17.4642
22 207 +- 14.3875
26 115 +- 10.723
30 82 +- 9.05539
34 107 +- 10.3441
38 125 +- 11.1803
42 65 +- 8.06226
46 62 +- 7.87401
50 70 +- 8.3666
54 54 +- 7.34847
58 62 +- 7.87401
62 44 +- 6.63325
66 33 +- 5.74456
70 39 +- 6.245
74 43 +- 6.55744
78 37 +- 6.08276
82 34 +- 5.83095
86 25 +- 5
90 38 +- 6.16441
94 26 +- 5.09902
98 34 +- 5.83095

Fig 2b. ZDC west spectra obtained with the minimum bias sample after the rho^0 selection cuts are applied.

Energy deposit (arb. units) Entries (arb. units)
2 0 +- 0
6 8 +- 2.82843
10 85 +- 9.21954
14 310 +- 17.6068
18 278 +- 16.6733
22 139 +- 11.7898
26 78 +- 8.83176
30 116 +- 10.7703
34 147 +- 12.1244
38 100 +- 10
42 77 +- 8.77496
46 54 +- 7.34847
50 69 +- 8.30662
54 55 +- 7.4162
58 62 +- 7.87401
62 48 +- 6.9282
66 25 +- 5
70 38 +- 6.16441
74 39 +- 6.245
78 36 +- 6
82 34 +- 5.83095
86 36 +- 6
90 30 +- 5.47723
94 29 +- 5.38516
98 27 +- 5.19615

Fig 3a.The invariant mass distribution for the coherently produced rho^{0} candidates from the minimum bias sample with the cut on the rho^{0} transverse momentum p_T < 150~MeV/c.

Inv. Mass (GeV/c) Entries (arb. units) (signal) Entries (arb. units) (background)
0.5075 111 +- 10.5357 25.2575 +- 7.00517
0.5225 84 +- 9.16515 36.9148 +- 8.46884
0.5375 96 +- 9.79796 38.8577 +- 8.68885
0.5525 110 +- 10.4881 44.6864 +- 9.31775
0.5675 95 +- 9.74679 44.6864 +- 9.31775
0.5825 109 +- 10.4403 36.9148 +- 8.46884
0.5975 130 +- 11.4018 27.2004 +- 7.26961
0.6125 158 +- 12.5698 31.0862 +- 7.77154
0.6275 143 +- 11.9583 44.6864 +- 9.31775
0.6425 152 +- 12.3288 27.2004 +- 7.26961
0.6575 196 +- 14 25.2575 +- 7.00517
0.6725 194 +- 13.9284 38.8577 +- 8.68885
0.6875 203 +- 14.2478 29.1433 +- 7.52476
0.7025 215 +- 14.6629 17.486 +- 5.82866
0.7175 269 +- 16.4012 31.0862 +- 7.77154
0.7325 281 +- 16.7631 29.1433 +- 7.52476
0.7475 312 +- 17.6635 21.3717 +- 6.44382
0.7625 312 +- 17.6635 15.5431 +- 5.49531
0.7775 285 +- 16.8819 17.486 +- 5.82866
0.7925 207 +- 14.3875 23.3146 +- 6.73035
0.8075 163 +- 12.7671 40.8006 +- 8.90342
0.8225 123 +- 11.0905 19.4289 +- 6.14394
0.8375 108 +- 10.3923 11.6573 +- 4.75908
0.8525 89 +- 9.43398 19.4289 +- 6.14394
0.8675 71 +- 8.42615 17.486 +- 5.82866
0.8825 61 +- 7.81025 5.82866 +- 3.36518
0.8975 52 +- 7.2111 15.5431 +- 5.49531
0.9125 40 +- 6.32456 7.77154 +- 3.88577
0.9275 33 +- 5.74456 13.6002 +- 5.14039
0.9425 32 +- 5.65685 9.71443 +- 4.34442
0.9575 23 +- 4.79583 7.77154 +- 3.88577
0.9725 23 +- 4.79583 1.94289 +- 1.94289
0.9875 15 +- 3.87298 19.4289 +- 6.14394
1.0025 16 +- 4 17.486 +- 5.82866
1.0175 14 +- 3.74166 5.82866 +- 3.36518
1.0325 11 +- 3.31662 7.77154 +- 3.88577
1.0475 12 +- 3.4641 5.82866 +- 3.36518
1.0625 12 +- 3.4641 1.94289 +- 1.94289
1.0775 10 +- 3.16228 1.94289 +- 1.94289
1.0925 8 +- 2.82843 5.82866 +- 3.36518

Fig 3b The invariant mass distribution for the coherently produced rho^{0} candidates obtained from the topology sample with the cut on the rho^{0} transverse momentum p_T < 150~MeV/c.

Inv. Mass (GeV/c) Entries (arb. units) (signal) Entries (arb. units) (background)
0.5075 1453.11 +- 181.143 484.371 +- 96.0831
0.5225 1381.54 +- 161.472 363.563 +- 75.5076
0.5375 1457.69 +- 162.75 628.806 +- 100.193
0.5525 1435.05 +- 146.329 411.694 +- 72.2194
0.5675 1463.89 +- 147.346 423.44 +- 73.8754
0.5825 1823.11 +- 160.336 414.838 +- 69.493
0.5975 2362.58 +- 187.072 519.995 +- 79.2443
0.6125 2611.76 +- 190.687 530.676 +- 76.8187
0.6275 3270.66 +- 211.785 511.041 +- 74.1766
0.6425 3207.92 +- 200.473 292.486 +- 53.3115
0.6575 4140.51 +- 229.296 295.071 +- 53.6234
0.6725 4680.57 +- 241.581 154.504 +- 37.7021
0.6875 6052.6 +- 278.532 270.872 +- 50.717
0.7025 6262.24 +- 268.024 235.993 +- 44.9009
0.7175 7299.3 +- 296.414 391.193 +- 59.5311
0.7325 8257.07 +- 314.688 312.242 +- 52.4156
0.7475 9525.12 +- 344.773 249.754 +- 46.6505
0.7625 9826.39 +- 355.243 202.153 +- 42.3513
0.7775 7661.59 +- 299.194 202.902 +- 40.816
0.7925 5569.66 +- 246.738 197.786 +- 39.8244
0.8075 4813.48 +- 232.22 142.739 +- 33.8492
0.8225 3994.59 +- 213.682 187.246 +- 38.6359
0.8375 3084.74 +- 188.999 135.505 +- 33.19
0.8525 2718.77 +- 175.55 151.846 +- 33.6567
0.8675 2242.12 +- 160.448 178.182 +- 37.1527
0.8825 1753.07 +- 139.483 150.068 +- 32.842
0.8975 1498.52 +- 129.197 168.058 +- 35.4228
0.9125 1192.58 +- 114.921 117.947 +- 28.7335
0.9275 1089.63 +- 113.011 195.574 +- 39.1446
0.9425 946.45 +- 103.607 139.541 +- 30.9049
0.9575 888.603 +- 105.112 100.978 +- 27.2982
0.9725 617.589 +- 81.9746 89.0753 +- 24.3405
0.9875 710.679 +- 101.19 93.3214 +- 27.541
1.0025 546.823 +- 80.9996 85.4412 +- 23.8917
1.0175 527.229 +- 85.6262 144.988 +- 35.3161
1.0325 517.2 +- 90.3626 125.985 +- 33.4124
1.0475 573.455 +- 105.349 135.818 +- 37.4787
1.0625 350.145 +- 60.9534 48.1449 +- 15.8742
1.0775 414.638 +- 84.4623 121.532 +- 35.0291
1.0925 422.053 +- 90.1085 102.316 +- 31.1905

Fig 4. The ratio |B/A| as a function of y_{rho^{0}} for the minimum bias data.

y |B/A| [(GeV/c)^-1/2]
-0.666667 0.806996 +- 0.0946242
-0.4 0.900944 +- 0.0702184
-0.133333 0.770651 +- 0.0743819
0.133333 0.837526 +- 0.0724432
0.4 0.922516 +- 0.0739404
0.666667 0.854197 +- 0.0701619

Fig 5. Coherent rho^{0} production cross-section for the minimum bias data set as a function of y_{rho^{0}} (black dots) overlaid by the d\sigma/dy distribution predicted by the KN model.

y dsigma/dy (mb) dsigma/dy (mb) (KN model)
-0.875 7.38985 +- 1.12461 6.58047
-0.625 7.81321 +- 0.722636 7.04088
-0.375 8.20018 +- 0.619612 7.33198
-0.125 7.87737 +- 0.581812 7.50925
0.125 7.85016 +- 0.61181 7.49827
0.375 6.84852 +- 0.506114 7.35077
0.625 7.05787 +- 0.63614 7.05056
0.875 6.16483 +- 0.902581 6.64129

Fig 6. rho^{0} production cross-section as a function of the momentum transfer squared t.

t [(GeV/c)^2] d^2sigma/dydt (mb/GeV^2)
0.0003125 631.395 +- 79.0616
0.0009375 739.913 +- 85.2418
0.0015625 975.882 +- 93.959
0.0021875 1010.81 +- 94.9499
0.003125 738.239 +- 54.9854
0.004375 418.67 +- 39.6641
0.0075 148.718 +- 12.1737
0.0185 25.9896 +- 3.21927
0.0385 13.2147 +- 2.22761
0.075 14.1144 +- 1.18585
0.125 7.4714 +- 1.73707
0.175 4.66357 +- 1.3573
0.225 3.85517 +- 0.837064
0.275 1.45558 +- 1.06268

Fig 7. Comparison of theoretical predictions to the measured differential cross-section for coherent rho^{0} production.


Model by V. P. Goncalves and M. V. T. Machado, Eur. Phys. J. C40, 519 (2005)

y dsigma/dy (mb)
-3.55 0.162237
-3.45 0.7489
-3.35 2.16093
-3.25 4.7558
-3.15 8.77905
-3.05 14.3307
-2.95 21.3684
-2.85 29.7326
-2.75 39.1814
-2.65 49.4262
-2.55 60.164
-2.45 71.1029
-2.35 81.9806
-2.25 92.5766
-2.15 102.717
-2.05 112.277
-1.95 121.176
-1.85 129.373
-1.75 136.858
-1.65 143.646
-1.55 149.771
-1.45 155.274
-1.35 160.205
-1.25 164.611
-1.15 168.54
-1.05 172.034
-0.95 175.129
-0.85 177.859
-0.75 180.248
-0.65 182.318
-0.55 184.086
-0.45 185.564
-0.35 186.762
-0.25 187.688
-0.15 188.346
-0.05 188.739
0.05 188.87
0.15 188.739
0.25 188.346
0.35 187.688
0.45 186.762
0.55 185.564
0.65 184.086
0.75 182.318
0.85 180.248
0.95 177.859
1.05 175.129
1.15 172.034
1.25 168.54
1.35 164.611
1.45 160.205
1.55 155.274
1.65 149.771
1.75 143.646
1.85 136.858
1.95 129.373
2.05 121.176
2.15 112.277
2.25 102.717
2.35 92.5766
2.45 81.9806
2.55 71.1029
2.65 60.164
2.75 49.4262
2.85 39.1814
2.95 29.7326
3.05 21.3684
3.15 14.3307
3.25 8.77905
3.35 4.7558
3.45 2.16093
3.55 0.7489
3.65 0.162237

Model by L. Frankfurt, M. Strikman and M. Zhalov, Phys. Lett. B537, 51 (2002)

y dsigma/dy (mb)
-3.5 30.4603
-3.3 44.9896
-3.1 66.0362
-2.9 93.8526
-2.7 123.168
-2.5 148.023
-2.3 165.339
-2.1 174.926
-1.9 177.551
-1.7 174.37
-1.5 166.66
-1.3 155.859
-1.1 146.382
-0.9 140.059
-0.7 134.722
-0.5 130.919
-0.3 128.447
-0.1 127.044
0.1 127.044
0.3 128.447
0.5 130.919
0.7 134.722
0.9 140.059
1.1 146.382
1.3 155.859
1.5 166.66
1.7 174.37
1.9 177.551
2.1 174.926
2.3 165.339
2.5 148.023
2.7 123.168
2.9 93.8526
3.1 66.0362
3.3 44.9896
3.5 30.4603

Model by S. Klein and J. Nystrand, Phys. Rev. C60, 014903 (1999)

y dsigma/dy (mb)
-3.5 9.79472
-3.3 18.9471
-3.1 36.401
-2.9 62.4181
-2.7 91.3475
-2.5 112.085
-2.3 125.457
-2.1 134.086
-1.9 130.892
-1.7 125.493
-1.5 126.695
-1.3 113.214
-1.1 110.922
-0.9 103.018
-0.7 97.5368
-0.5 95.492
-0.3 88.1459
-0.1 87.058
0.1 85.2407
0.3 89.6415
0.5 94.5579
0.7 97.1969
0.9 99.8861
1.1 106.788
1.3 115.366
1.5 122.042
1.7 135.33
1.9 132.706
2.1 132.436
2.3 125.111
2.5 119.057
2.7 92.916
2.9 64.5927
3.1 38.1132
3.3 19.2118
3.5 10.4339

Measured

y dsigma/dy (mb)
-0.875 94.9849 +- 19.814
-0.625 84.5656 +- 7.62107
-0.375 83.9829 +- 5.80888
-0.125 86.3201 +- 6.82082
0.125 93.8674 +- 8.96162
0.375 73.9641 +- 5.93775
0.625 88.6657 +- 10.8323
0.875 65.9216 +- 11.878

Fig 8a. Projection (Phi_{h}) of the two dimensional efficiency corrected Phi_{h} vs cos(Theta_{h}) distributions obtained with the minimum bias data set.

Phi_{h} (rad) Entries (arb. units) (mb)
-2.5 348.773 +- 22.7481
-1.5 254.391 +- 22.1797
-0.5 313.179 +- 22.8407
0.5 326.042 +- 21.5501
1.5 251.053 +- 19.7214
2.5 299.784 +- 21.2776

Fig 8b. Projection (cos(Theta_{h})) of the two dimensional efficiency corrected Phi_{h} vs cos(Theta_{h}) distributions obtained with the minimum bias data set.

cos(Theta_{h}) Entries (arb. units) (mb)
-0.75 80.1759 +- 14.3796
-0.4 271.06 +- 23.5615
-0.2 359.56 +- 24.744
0 366.006 +- 23.5896
0.2 372.453 +- 23.2057
0.4 242.294 +- 20.7568
0.75 110.556 +- 15.0802

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