13 Eq. 2 to account for detector resolution and for losses due to bremsstrahlung which result in a tail to low values of invariant mass. The fit is done using the integral of the fit function in each bin, and is shown as the dashed-line histogram. We discuss next the procedure used to extract the continuum contributions (dot-dashed line) and the Υ(1S+2S+3S) yield. The Drell-Yan continuum is parameterized from a pQCD NLO calculation [32] done in the kinematic range | y$_{Υ}$ | < 0 . 5 and m > 4 GeV /c $^{2}$. We convolute the cal- culated spectrum with the detector resolution (account- ing for bremsstrahlung), but this introduces very small changes in the shape of the spectrum. We find that the shape of the Drell-Yan continuum is well described by a function of the form with the parameters m$_{0}$ = 2 . 70 GeV /c 2 and n = 4 . 59. The b - ¯ b contribution is parameterized from a simula- tion using PYTHIA 8 [25]. We turn on production of b - ¯ b pairs, and follow their fragmentation and subsequent decays of the B hadrons to look for dielectrons origi- nating from the b quarks. We convolute the simulated shape with the detector resolution and bremsstrahlung, and find that the shape is well described by a function of the form with the parameters b = 1 . 59, m$_{0}$ = 29 . 7 GeV /c $^{2}$, and c = 26 . 6. Since the STAR Υ trigger is meant to reject events with low invariant mass, we parametrize the trigger response on both continuum contributions by multiplying them with an error function where m$_{trig}$ is related to the trigger thresholds and w describes the width of the turn-on of the error function due to finite detector resolution. We obtain the parame- ters from the like-sign data (Fig. 10) by multiplying the error function with an exponential exp( − m/T ) to ac- count for the random like-sign combinations at higher mass. We use the like-sign data since the trigger turn-on shape for like-sign and unlike-sign pairs is the same in our detector, but the like-sign invariant mass distribu- tion is purely due to combinatorics and can be fit with the simple parametrization given above (Fig. 10, dashed line). The parameters are m$_{trig}$ = 8 . 1 ± 0 . 8 GeV /c 2 and w = 1 . 8 ± 0 . 5 GeV /c $^{2}$. To obtain the Υ yields and cross section, we perform a fit of the unlike-sign invariant mass distribution after subtracting the like-sign background including contribu- tions for the Υ(1S+2S+3S), and the continuum due to Drell-Yan and b - ¯ b . Since the extracted Υ yield from the fit will be sensitive to the continuum yield, we next dis- cuss the effect that variations of the Drell-Yan and b - ¯ b cross sections can have on our result. We find that the resulting shapes of the two continuum contributions are very similar. We can fit the continuum yield using the parameterized Drell-Yan and b - ¯ b contri- butions. The 1- and 2- σ contours in the 2-D parameter space σ$_{b}$$_{-}$ ¯ b vs. σ$_{DY}$ are shown in Fig. 12, where the cross sections quoted are corrected for efficiency and accep- tance, and measured in the phase space region | y | < 0 . 5 and 8 < m$_{ee}$ < 11 GeV /c $^{2}$. The fit shows a strong anti-correlation between the Drell-Yan and the b - ¯ b cross sections due to the simi- larity of the parameterized shapes. The shape of the Drell-Yan is slightly favored by our data, and we ob- tain the minimal χ 2 for a Drell-Yan cross section of ≈ 38 pb with a negligible b - ¯ b contribution. The fit gives χ $^{2}$/ NDF = 1 . 1. The prediction from an NLO calculation of the Drell-Yan cross section [32] is shown as the ver- tical line at 38.6 pb, and is consistent with values in the 1- σ region (horizontal lines). Our data also allow values of the b - ¯ b cross section up to ≈ 15 pb within the 1- σ range, provided the Drell-Yan yield is reduced. Given the anti-correlation, our data are mainly sensitive to the sum of the two cross sections, and within the 1- σ con- B. Drell-Yan and b - ¯ b Continuum Contributions A (1 + m/m$_{0}$ ) n (4) Am b (1 + m/m$_{0}$ ) c (5) erf(( m − m$_{trig}$ ) /w ) + 1 2 (6) FIG. 12: The 1- σ (horizontal lines) and 2- σ (diagonal lines) contours obtained by fitting the data, showing the favored regions for the Drell-Yan and b - ¯ b cross sections. The dashed line shows the prediction for the Drell-Yan cross section from a pQCD NLO calculation [32]. /dy (pb) Drell-Yan d 0 10 20 30 40 50 60 70 80 /dy (pb)  d b b- 10 20 30 40 50 60  Contour 2  Contour 1  vs. Drell-Yan b b- , |y|<0.5 2  < 11 GeV/c ee 8< m Drell-Yan NLO pQCD