ρ0 Production and Possible Modification in Au+Au and p+p Collisions at sqrt(sNN)=200 GeV

ρ⁰ Production and Possible Modification in Au+Au and p+p Collisions at sqrt(s_NN)=200 GeV
J. Adams et al. , Phys. Rev. Lett. 92 , 092301 (2004).

Figure 1: Raw π⁺π^- invariant mass distributions.

Errors are statistical only.

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Like-sign subtracted invariant mass distribution from minimum bias p+p interactions
0.6 <= pT < 0.8 GeV/c
M_inv [GeV/c²]	counts/(10 MeV/c²)
0.405	3600 +/- 450
0.415	2960 +/- 450
0.425	3650 +/- 450
0.435	4660 +/- 440
0.445	5770 +/- 440
0.455	5260 +/- 440
0.465	8390 +/- 440
0.475	12260 +/- 440
0.485	17250 +/- 440
0.495	18700 +/- 440
0.505	7850 +/- 430
0.515	4730 +/- 420
0.525	4530 +/- 420
0.535	5050 +/- 410
0.545	5110 +/- 410
0.555	4650 +/- 400
0.565	4030 +/- 400
0.575	4210 +/- 400
0.585	4920 +/- 390
0.595	4320 +/- 390
0.605	4590 +/- 380
0.615	4170 +/- 380
0.625	5200 +/- 370
0.635	4600 +/- 370
0.645	4510 +/- 370
0.655	4870 +/- 360
0.665	5530 +/- 360
0.675	5530 +/- 360
0.685	5730 +/- 350
0.695	5830 +/- 350
0.705	6700 +/- 350
0.715	6820 +/- 350
0.725	6650 +/- 340
0.735	6330 +/- 340
0.745	7030 +/- 340
0.755	6820 +/- 330
0.765	6730 +/- 330
0.775	6160 +/- 330
0.785	5470 +/- 320
0.795	5000 +/- 320
0.805	3880 +/- 320
0.815	4370 +/- 310
0.825	3130 +/- 310
0.835	4000 +/- 310
0.845	2370 +/- 310
0.855	2490 +/- 310
0.865	2490 +/- 300
0.875	2480 +/- 300
0.885	1620 +/- 300
0.895	2300 +/- 300
0.905	1880 +/- 300
0.915	2460 +/- 300
0.925	1920 +/- 300
0.935	2940 +/- 290
0.945	2460 +/- 290
0.955	2420 +/- 290
0.965	2470 +/- 290
0.975	2660 +/- 290
0.985	2220 +/- 280
0.995	1570 +/- 280
1.005	1400 +/- 270
1.015	1410 +/- 270
1.025	1600 +/- 270
1.035	1170 +/- 260
1.045	1250 +/- 260
1.055	1060 +/- 260
1.065	1130 +/- 250
1.075	860 +/- 250
1.085	680 +/- 250
1.095	1160 +/- 240
1.105	1270 +/- 240
1.115	700 +/- 240
1.125	1240 +/- 230
1.135	980 +/- 230
1.145	1110 +/- 230
1.155	940 +/- 220
1.165	720 +/- 220
1.175	1080 +/- 220
1.185	870 +/- 210
1.195	810 +/- 210
1.205	1250 +/- 210
1.215	840 +/- 210
1.225	780 +/- 200
1.235	570 +/- 200
1.245	1000 +/- 200
1.255	790 +/- 190
1.265	980 +/- 190
1.275	660 +/- 190
1.285	620 +/- 180
1.295	560 +/- 180
1.305	560 +/- 180
1.315	630 +/- 180
1.325	380 +/- 170
1.335	310 +/- 170
1.345	570 +/- 170
1.355	320 +/- 170
1.365	-20 +/- 160
1.375	200 +/- 160
1.385	270 +/- 160
1.395	190 +/- 160
1.405	380 +/- 150
1.415	300 +/- 150
1.425	340 +/- 150
1.435	230 +/- 150
1.445	90 +/- 140
1.455	-170 +/- 140
1.465	120 +/- 140
1.475	210 +/- 140
1.485	-20 +/- 140
1.495	-10 +/- 130
1.505	210 +/- 130

Like-sign subtracted invariant mass distribution from peripheral Au+Au collisions
0.6 <= pT < 0.8 GeV/c
M_inv [GeV/c²]	counts/(10 MeV/c²)
0.405	31600 +/- 2800
0.415	27000 +/- 2800
0.425	25300 +/- 2800
0.435	31400 +/- 2800
0.445	25100 +/- 2800
0.455	33200 +/- 2800
0.465	29700 +/- 2800
0.475	44800 +/- 2800
0.485	59500 +/- 2800
0.495	70700 +/- 2800
0.505	30300 +/- 2700
0.515	21700 +/- 2700
0.525	28500 +/- 2700
0.535	26500 +/- 2700
0.545	15700 +/- 2700
0.555	18900 +/- 2600
0.565	20200 +/- 2600
0.575	14300 +/- 2600
0.585	18700 +/- 2600
0.595	14400 +/- 2600
0.605	15800 +/- 2500
0.615	16000 +/- 2500
0.625	11800 +/- 2500
0.635	15800 +/- 2500
0.645	15200 +/- 2400
0.655	14500 +/- 2400
0.665	12800 +/- 2400
0.675	19000 +/- 2400
0.685	17300 +/- 2400
0.695	17900 +/- 2300
0.705	19700 +/- 2300
0.715	15800 +/- 2300
0.725	13700 +/- 2300
0.735	13100 +/- 2300
0.745	12900 +/- 2300
0.755	13600 +/- 2200
0.765	8200 +/- 2200
0.775	12900 +/- 2200
0.785	6400 +/- 2200
0.795	10100 +/- 2200
0.805	3600 +/- 2200
0.815	8300 +/- 2200
0.825	5000 +/- 2100
0.835	4100 +/- 2100
0.845	6000 +/- 2100
0.855	3600 +/- 2100
0.865	4700 +/- 2100
0.875	-1800 +/- 2100
0.885	8900 +/- 2100
0.895	7300 +/- 2100
0.905	4900 +/- 2100
0.915	4000 +/- 2100
0.925	4300 +/- 2100
0.935	8500 +/- 2100
0.945	3300 +/- 2100
0.955	3400 +/- 2100
0.965	4200 +/- 2000
0.975	3800 +/- 2000
0.985	8700 +/- 2000
0.995	5200 +/- 2000
1.005	5000 +/- 2000
1.015	400 +/- 2000
1.025	2800 +/- 1900
1.035	2300 +/- 1900
1.045	3500 +/- 1900
1.055	400 +/- 1900
1.065	5700 +/- 1800
1.075	900 +/- 1800
1.085	1200 +/- 1800
1.095	4100 +/- 1800
1.105	-700 +/- 1800
1.115	2300 +/- 1700
1.125	1500 +/- 1700
1.135	-200 +/- 1700
1.145	1700 +/- 1700
1.155	-1800 +/- 1600
1.165	1300 +/- 1600
1.175	-900 +/- 1600
1.185	-2200 +/- 1600
1.195	4100 +/- 1600
1.205	-200 +/- 1500
1.215	3000 +/- 1500
1.225	1900 +/- 1500
1.235	-1200 +/- 1500
1.245	1200 +/- 1500
1.255	900 +/- 1400
1.265	300 +/- 1400
1.275	2800 +/- 1400
1.285	-2300 +/- 1400
1.295	3500 +/- 1400
1.305	-1800 +/- 1300
1.315	-1900 +/- 1300
1.325	800 +/- 1300
1.335	1300 +/- 1300
1.345	400 +/- 1300
1.355	-50 +/- 1300
1.365	-400 +/- 1200
1.375	-700 +/- 1200
1.385	-2000 +/- 1200
1.395	200 +/- 1200
1.405	-700 +/- 1200
1.415	1300 +/- 1200
1.425	900 +/- 1100
1.435	900 +/- 1100
1.445	300 +/- 1100
1.455	400 +/- 1100
1.465	-1200 +/- 1100
1.475	1300 +/- 1100
1.485	600 +/- 1100
1.495	100 +/- 1000
1.505	-300 +/- 1000

Invariant mass from peripheral Au+Au collisions from inserted plot
0.6 <= pT < 0.8 GeV/c
Raw π⁺π^- invariant mass distribution (solid line)
M_inv [GeV/c²]	counts/(10 MeV/c²)
0.275	152490 +/- 390
0.285	1975200 +/- 1400
0.295	3089400 +/- 1800
0.305	3593100 +/- 1900
0.315	3774300 +/- 1900
0.325	3842000 +/- 2000
0.335	3893500 +/- 2000
0.345	3931300 +/- 2000
0.355	3958000 +/- 2000
0.365	3985500 +/- 2000
0.375	3998300 +/- 2000
0.385	4008600 +/- 2000
0.395	4011000 +/- 2000
0.405	4006600 +/- 2000
0.415	3993300 +/- 2000
0.425	3979300 +/- 2000
0.435	3966900 +/- 2000
0.445	3941000 +/- 2000
0.455	3921200 +/- 2000
0.465	3893200 +/- 2000
0.475	3872800 +/- 2000
0.485	3854500 +/- 2000
0.495	3827900 +/- 2000
0.505	3749600 +/- 1900
0.515	3698500 +/- 1900
0.525	3654300 +/- 1900
0.535	3609000 +/- 1900
0.545	3551800 +/- 1900
0.555	3503500 +/- 1900
0.565	3452100 +/- 1900
0.575	3396100 +/- 1800
0.585	3337600 +/- 1800
0.595	3280500 +/- 1800
0.605	3222700 +/- 1800
0.615	3163900 +/- 1800
0.625	3102500 +/- 1800
0.635	3051000 +/- 1700
0.645	2993400 +/- 1700
0.655	2942000 +/- 1700
0.665	2887400 +/- 1700
0.675	2841400 +/- 1700
0.685	2791700 +/- 1700
0.695	2747000 +/- 1700
0.705	2701800 +/- 1600
0.715	2660000 +/- 1600
0.725	2619300 +/- 1600
0.735	2580300 +/- 1600
0.745	2544500 +/- 1600
0.755	2512600 +/- 1600
0.765	2477300 +/- 1600
0.775	2446700 +/- 1600
0.785	2414400 +/- 1600
0.795	2387200 +/- 1500
0.805	2357200 +/- 1500
0.815	2334400 +/- 1500
0.825	2308400 +/- 1500
0.835	2285100 +/- 1500
0.845	2265500 +/- 1500
0.855	2245600 +/- 1500
0.865	2230700 +/- 1500
0.875	2217800 +/- 1500
0.885	2219000 +/- 1500
0.895	2212600 +/- 1500
0.905	2202600 +/- 1500
0.915	2191500 +/- 1500
0.925	2179300 +/- 1500
0.935	2165800 +/- 1500
0.945	2145400 +/- 1500
0.955	2124400 +/- 1500
0.965	2096200 +/- 1400
0.975	2063400 +/- 1400
0.985	2032400 +/- 1400
0.995	1991300 +/- 1400
1.005	1951600 +/- 1400
1.015	1909900 +/- 1400
1.025	1869200 +/- 1400
1.035	1830900 +/- 1400
1.045	1789300 +/- 1300
1.055	1746800 +/- 1300
1.065	1708900 +/- 1300
1.075	1667200 +/- 1300
1.085	1625500 +/- 1300
1.095	1587000 +/- 1300
1.105	1546300 +/- 1200
1.115	1509400 +/- 1200
1.125	1470700 +/- 1200
1.135	1432900 +/- 1200
1.145	1395500 +/- 1200
1.155	1358800 +/- 1200
1.165	1325100 +/- 1200
1.175	1290000 +/- 1100
1.185	1255000 +/- 1100
1.195	1224900 +/- 1100
1.205	1190400 +/- 1100
1.215	1159600 +/- 1100
1.225	1128700 +/- 1100
1.235	1097100 +/- 1000
1.245	1068800 +/- 1000
1.255	1040400 +/- 1000
1.265	1012100 +/- 1000
1.275	985410 +/- 990
1.285	958120 +/- 980
1.295	934220 +/- 970
1.305	905910 +/- 950
1.315	882470 +/- 940
1.325	860880 +/- 930
1.335	836830 +/- 910
1.345	815370 +/- 900
1.355	792440 +/- 890
1.365	772070 +/- 880
1.375	750250 +/- 870
1.385	729960 +/- 850
1.395	712050 +/- 840
1.405	692700 +/- 830
1.415	674500 +/- 820
1.425	656310 +/- 810
1.435	639160 +/- 800
1.445	620650 +/- 790
1.455	605190 +/- 780
1.465	586800 +/- 770
1.475	573840 +/- 760
1.485	558040 +/- 750
1.495	543180 +/- 740
1.505	528090 +/- 730
1.515	513050 +/- 720
1.525	500960 +/- 710
1.535	487660 +/- 700
1.545	474600 +/- 690
1.555	462050 +/- 680
1.565	449740 +/- 670
1.575	438710 +/- 660
1.585	426900 +/- 650
1.595	416370 +/- 650
1.605	405790 +/- 640
1.615	394010 +/- 630
1.625	384260 +/- 620
1.635	373350 +/- 610
1.645	365040 +/- 600
1.655	354260 +/- 600
1.665	345030 +/- 590
1.675	336690 +/- 580
1.685	327180 +/- 570
1.695	319350 +/- 570
1.705	311850 +/- 560
1.715	302740 +/- 550
1.725	296360 +/- 540
1.735	288160 +/- 540
1.745	279880 +/- 530
1.755	273080 +/- 520
1.765	266710 +/- 520
1.775	259080 +/- 510
1.785	253070 +/- 500
1.795	245720 +/- 500
1.805	240090 +/- 490
1.815	234440 +/- 480
1.825	228070 +/- 480
1.835	222170 +/- 470
1.845	216480 +/- 470
1.855	211630 +/- 460
1.865	205490 +/- 450
1.875	200370 +/- 450
1.885	195140 +/- 440
1.895	190600 +/- 440
1.905	186010 +/- 430
1.915	180900 +/- 430
1.925	175930 +/- 420
1.935	171500 +/- 410
1.945	167770 +/- 410
1.955	163100 +/- 400
1.965	159890 +/- 400
1.975	155510 +/- 390
1.985	152270 +/- 390
1.995	148260 +/- 390
2.005	143880 +/- 380
2.015	140620 +/- 370
2.025	136810 +/- 370
2.035	133890 +/- 370
2.045	130070 +/- 360
2.055	126740 +/- 360
2.065	123330 +/- 350
2.075	119800 +/- 350
2.085	117220 +/- 340
2.095	114890 +/- 340
2.105	112030 +/- 330
2.115	108270 +/- 330
2.125	105500 +/- 320
2.135	103090 +/- 320
2.145	100280 +/- 320
2.155	98050 +/- 310
2.165	95350 +/- 310
2.175	93040 +/- 310
2.185	90280 +/- 300
2.195	88740 +/- 300
2.205	86080 +/- 290
2.215	83510 +/- 290
2.225	81880 +/- 290
2.235	79690 +/- 280
2.245	77730 +/- 280
2.255	75740 +/- 280
2.265	74110 +/- 270
2.275	71980 +/- 270
2.285	69810 +/- 260
2.295	68080 +/- 260
2.305	66250 +/- 260
2.315	64840 +/- 250
2.325	63300 +/- 250
2.335	61590 +/- 250
2.345	59700 +/- 240
2.355	58570 +/- 240
2.365	56820 +/- 240
2.375	55360 +/- 240
2.385	54030 +/- 230
2.395	52520 +/- 230
2.405	51730 +/- 230
2.415	50050 +/- 220
2.425	49190 +/- 220
2.435	47680 +/- 220
2.445	46750 +/- 220
2.455	45130 +/- 210
2.465	44160 +/- 210
2.475	43190 +/- 210
2.485	41940 +/- 200
2.495	41120 +/- 200

0.6 <= pT < 0.8 GeV/c
Like-Sign reference distribution (open circles)
M_inv [GeV/c²]	counts/(10 MeV/c²)
0.28	1573190 +/- 440
0.36	3920720 +/- 700
0.44	3915790 +/- 700
0.52	3647150 +/- 680
0.6	3234930 +/- 640
0.68	2804080 +/- 590
0.76	2486430 +/- 560
0.84	2276390 +/- 530
0.92	2174490 +/- 520
1	1964080 +/- 500
1.08	1645370 +/- 450
1.16	1343670 +/- 410
1.24	1084240 +/- 370
1.32	873270 +/- 330
1.4	703450 +/- 300
1.48	566200 +/- 270
1.56	456560 +/- 240
1.64	369430 +/- 220
1.72	299070 +/- 190
1.8	243440 +/- 170
1.88	198210 +/- 160
1.96	161550 +/- 140
2.04	131680 +/- 130
2.12	107390 +/- 120
2.2	87400 +/- 100
2.28	71326. +/- 95.
2.36	57974. +/- 85.
2.44	47252. +/- 77.

Figure 2: ρ⁰ mass as a function of p_T.

Mass is obtained by fitting the data to relativistic Breit-Wigner functions multiplined by a Boltzmann factor to account for phase space. Errors are listed as statistical and asymmetric systematic, separately.

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Mass from minimum bias p+p interactions
p_T [GeV/c]	Mass [GeV/c²]
0.3	0.7294 +/- 0.0012 (stat) + 0.0213 - 0.0103(sys)
0.5	0.7405 +/- 0.0014 (stat) + 0.0192 - 0.0103(sys)
0.7	0.7472 +/- 0.0018 (stat) + 0.0110 - 0.0103(sys)
0.9	0.7451 +/- 0.0021 (stat) + 0.0105 - 0.0105(sys)
1.1	0.7474 +/- 0.0027 (stat) + 0.0107 - 0.0107(sys)
1.3	0.7432 +/- 0.0026 (stat) + 0.0110 - 0.0110(sys)
1.5	0.7555 +/- 0.0032 (stat) + 0.0120 - 0.0120(sys)
1.7	0.7470 +/- 0.0033 (stat) + 0.0114 - 0.0114(sys)
1.9	0.7473 +/- 0.0038 (stat) + 0.0125 - 0.0125(sys)
2.1	0.7467 +/- 0.0041 (stat) + 0.0120 - 0.0120(sys)
2.3	0.7466 +/- 0.0046 (stat) + 0.0149 - 0.0143(sys)
2.5	0.7473 +/- 0.0059 (stat) + 0.0164 - 0.0164(sys)
2.7	0.7455 +/- 0.0065 (stat) + 0.0158 - 0.0158(sys)
Mass from high multiplicity p+p interactions
0.3	0.7132 +/- 0.0026 (stat) + 0.0307 - 0.0108(sys)
0.5	0.7262 +/- 0.0028 (stat) + 0.0318 - 0.0105(sys)
0.7	0.7325 +/- 0.0035 (stat) + 0.0218 - 0.0113(sys)
0.9	0.7378 +/- 0.0037 (stat) + 0.0134 - 0.0134(sys)
1.1	0.7269 +/- 0.0046 (stat) + 0.0140 - 0.0118(sys)
1.3	0.7264 +/- 0.0037 (stat) + 0.0138 - 0.0113(sys)
1.5	0.7517 +/- 0.0058 (stat) + 0.0115 - 0.0115(sys)
1.7	0.7362 +/- 0.0049 (stat) + 0.0135 - 0.0135(sys)
1.9	0.7411 +/- 0.0057 (stat) + 0.0146 - 0.0137(sys)
2.1	0.7393 +/- 0.0056 (stat) + 0.0134 - 0.0134(sys)
2.3	0.7463 +/- 0.0061 (stat) + 0.0133 - 0.0133(sys)
2.5	0.7424 +/- 0.0078 (stat) + 0.0125 - 0.0125(sys)
2.7	0.7411 +/- 0.0093 (stat) + 0.0216 - 0.0200(sys)
Mass from peripheral Au+Au collisions:
0.3	0.7100 +/- 0.0072 (stat) + 0.0253 - 0.0216(sys)
0.5	0.7405 +/- 0.0062 (stat) + 0.0355 - 0.0170(sys)
0.7	0.7158 +/- 0.0044 (stat) + 0.0207 - 0.0170(sys)
0.9	0.7342 +/- 0.0059 (stat) + 0.0374 - 0.0186(sys)
1.1	0.7076 +/- 0.0064 (stat) + 0.0173 - 0.0173(sys)
1.3	0.7166 +/- 0.0064 (stat) + 0.0173 - 0.0173(sys)
1.5	0.7410 +/- 0.0050 (stat) + 0.0166 - 0.0166(sys)
1.7	0.7490 +/- 0.0072 (stat) + 0.0184 - 0.0184(sys)
1.9	0.764 +/- 0.010 (stat) + 0.031 - 0.031(sys)
2.1	0.759 +/- 0.012 (stat) + 0.031 - 0.031(sys)

Figure 3: Invariant p_T spectra.

Invariant p_T distributions for |y| < 0.5. Errors listed are statistical only. A power-law fit to the p+p spectrum yielded dN/dy = 0.259 +/- 0.002 (stat) +/- 0.039 (sys) and <p_T> = 0.616 +/- 0.002 (stat) +/- 0.062 (sys) GeV/c. An exponential fit in (m_T-m₀) to the Au+Au data yielded dN/dy = 5.4 +/- 0.1 (stat) +/- 1.2 (sys), and <p_T> = 0.83 +/- 0.01(stat) +/- 0.10 (sys) GeV/c.

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Spectra from minimum bias p+p interactions:
p_T[GeV/c]	(m_T-0.769) [GeV/c]	1/(2 π p_T) d²N/(dy dp_T) [(GeV/c)^-2]
0.3	0.056	0.1654 +/- 0.0017
0.5	0.148	0.0879 +/- 0.0010
0.7	0.271	0.03965 +/- 0.00065
0.9	0.415	0.02151 +/- 0.00038
1.1	0.573	0.00995 +/- 0.00022
1.3	0.741	0.00603 +/- 0.00013
1.5	0.917	0.002891 +/- 0.000082
1.7	1.097	0.001907 +/- 0.000054
1.9	1.281	0.001185 +/- 0.000038
2.1	1.467	0.000673 +/- 0.000024
2.3	1.656	0.000432 +/- 0.000016
2.5	1.847	0.000260 +/- 0.000013
2.7	2.038	0.0001540 +/- 0.0000090
Spectra from peripheral Au+Au collisions
0.3	0.056	1.89 +/- 0.12
0.5	0.148	1.530 +/- 0.082
0.7	0.271	1.133 +/- 0.053
0.9	0.415	0.715 +/- 0.034
1.1	0.573	0.408 +/- 0.020
1.3	0.741	0.205 +/- 0.011
1.5	0.917	0.1568 +/- 0.0070
1.7	1.097	0.0776 +/- 0.0045
1.9	1.281	0.0419 +/- 0.0031
2.1	1.467	0.0245 +/- 0.0020

Figure 4: ρ⁰/π ratio as function of cms energy.

Compilation of ρ⁰/π ratios from other experiments, along with the STAR measurements at 200 GeV. Errors on STAR ratios include statistical and systematic, summed quadratically.

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sqrt(s) [GeV]	ρ⁰/π	Source
6.84	0.073 +/- 0.009	ρ⁰/((π⁺+π^-+π⁰)/3) for p+p
7.82	0.16 +/- 0.01	ρ⁰/π^- for K⁺ + p
10.45	0.109 +/-0.016	ρ⁰/π⁰ for e⁺+e^-
19.6	0.25 +/-0.09	ρ⁰/π^- for π^- + p
19.7	0.13 +/- 0.02	ρ⁰/π^- for p + p
27.5	0.102 +/- 0.01	ρ⁰/(π⁺ + π^- + π⁰)/3 for p + p
29	0.139 +/-0.017	ρ⁰/π⁰ for e⁺+e^-
52.5	0.13 +/- 0.01	ρ⁰/π^- for p+p
91	0.130 +/- 0.013	ρ⁰/π⁰ for e⁺+e^-
200	0.183+/-0.027	ρ⁰/π^- for minimum bias p+p interactions
200	0.169+/-0.037	ρ⁰/π^- peripheral Au+Au collisions

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