1. Introduction
2. A review of simplified model
2.1. model introduction
2.2. experiment constrain
Figure 4. Contour plots of exclusion and discovery capability in the g* − mT plane at 3 TeV CLIC with ${P}_{{e}^{-}}=-0.8$. The red solid lines represent the limit from the LHC direct searches, the gray dashed lines represent the width-to-mass ratio ΓT/mT = 0.1, and the black solid lines represent the limit from T, S. The black and orange dashed lines represent the exclusion and discovery regions at different integrated luminosities without and with ISR, respectively. The purple line in the left panel stands for the result of T → Wb at 14 TeV HL-LHC [63], while there is no corresponding line in the right panel since the discovery region cannot reach the range of g* < 0.3. |
3. Beam polarization and ISR effect
Figure 1. Leading order Feynman diagram of the process ${e}^{+}{e}^{-}\to \bar{T}{W}^{+}b$. |
Figure 2. The left panel represents the polarization effect for different mT with g* = 0.2, where the black solid line denotes the enhancement ratio σPolar/σNo−Polar. The right panel represents the ISR effect for different mT with g* = 0.2 assuming ${P}_{{e}^{-}}=-0.8,{P}_{{e}^{+}}=0$, where the black and red solid lines denote cross sections σNo−ISR and σISR respectively. The blue solid line denotes the ratio σISR/σNo−ISR. |
Table 1. Cross sections without ISR (σNo−ISR) and with ISR (σISR) at the 3 TeV CLIC for g* = 0.2 and ${P}_{{e}^{-}}=-0.8,{P}_{{e}^{+}}=0$. |
Signal (ab) | Backgrounds (ab) | |||||
---|---|---|---|---|---|---|
T1400 | T1500 | T1600 | ${{tW}}^{-}\bar{b}$ | W+W−Z | W+W−H | |
σNo−ISR | 227.5 | 79 | 30 | 1700 | 270 | 66 |
σISR | 164 | 53 | 24.85 | 3860 | 350 | 100 |
σISR/σNo−ISR | 72.0% | 67.1% | 82.8% | 227.1% | 129.6% | 166.7% |
4. Event generation and analysis
• | ${e}^{+}{e}^{-}\to {W}^{+}b\bar{t}\to ({W}^{+}b)({W}^{-}\bar{b})\to ({l}^{+}\nu b)({jj}\bar{b})$ |
• | ${e}^{+}{e}^{-}\to {W}^{+}{W}^{-}Z\to ({l}^{+}\nu )({jj})(b\bar{b})$ |
• | ${e}^{+}{e}^{-}\to {W}^{+}{W}^{-}H\to ({l}^{+}\nu )({jj})(b\bar{b}).$ |
Figure 3. Normalized distributions of ${p}_{T}^{{l}_{1}}$, ${p}_{T}^{{j}_{2}}$, ${m}_{{j}_{2}}$, MET, ${\eta }_{{j}_{1}}$, and ${\eta }_{{l}_{1}}$ for the signal (mT = 1500 GeV and g* = 0.2) and backgrounds at the 3 TeV CLIC. The black arrows indicate the selected cuts. |
• | Trigger :1 < N(j) < 4, N(l) = 1 |
• | Cut 1: M(j2) < 100 GeV |
• | Cut 2: PT(j2) > 300 GeV |
• | Cut 3: − 1 < η(l) < 1 |
• | Cut 4: − 1 < η(j1) < 1 |
• | Cut 5: pT(l) > 200 GeV |
• | Cut 6: MET > 80 GeV |
Table 2. Cut flows of the signal and backgrounds at the 3 TeV CLIC with g* = 0.2 and ${P}_{{e}^{-}}=-0.8,{P}_{{e}^{+}}=0$. |
Cuts | Signal (ab) | Backgrounds (ab) | ||||
---|---|---|---|---|---|---|
T1400 | T1500 | T1600 | ${{tW}}^{-}\bar{b}$ | W+W−Z | W+W−H | |
Cross section | 227.5 | 79 | 30 | 1700 | 270 | 66 |
Trigger | 194.89 | 66.74 | 25.42 | 878.4 | 64.5 | 18.44 |
Cut 1 | 140.38 | 47.02 | 15.49 | 512.2 | 61.8 | 13.50 |
Cut 2 | 115.52 | 37.43 | 12.43 | 259.7 | 26.6 | 6.18 |
Cut 3 | 100.92 | 31.85 | 10.35 | 99.4 | 5.52 | 3.16 |
Cut 4 | 82.22 | 26.3 | 8.34 | 67.39 | 1.78 | 1.38 |
Cut 5 | 60.52 | 19.18 | 5.81 | 8.56 | 1.27 | 1.14 |
Cut 6 | 54.68 | 17.28 | 5.28 | 7.16 | 0.99 | 1.04 |
Total efficiency | 24.04% | 21.73% | 17.23% | 0.42% | 0.37% | 1.58% |
5. Exclusion and discovery significance
6. Summary
Table 3. Summary of exclusion and discovery regions. |
CLIC @ 3 TeV with ${ \mathcal L }=$ 5000 fb−1 and ${P}_{{e}^{-}}=-0.8,{P}_{{e}^{+}}=0$ | ||||
---|---|---|---|---|
Exclusion regions | Discovery regions | |||
g* | mT (GeV) | g* | mT (GeV) | |
No-ISR | $\left[0.05,0.23\right]$ | $\left[1270,1800\right]$ | $\left[0.05,0.23\right]$ | $\left[1270,1550\right]$ |
With-ISR | $\left[0.05,0.23\right]$ | $\left[1270,1600\right]$ | $\left[0.05,0.23\right]$ | $\left[1270,1500\right]$ |
Table 4. Comparison of results from searching for T at future colliders. |
Collider | L/fb−1 | Decay | Excluding region | Discovery region | Reference | ||
---|---|---|---|---|---|---|---|
g* | mT GeV−1 | g* | mT GeV−1 | ||||
14 TeV HL-LHC | 3000 | T → W+b → l+νb | $\left[0.19,0.5\right]$ | $\left[1300,2420\right]$ | $\left[0.31,0.5\right]$ | $\left[1300,1910\right]$ | [63] |
3000 | T → tZ → bjjl+l− | $\left[0.085,0.5\right]$ | $\left[1000,1840\right]$ | $\left[0.15,0.5\right]$ | $\left[1000,1580\right]$ | [69] | |
3000 | T → tZ → l+νbl+l− | $\left[0.06,0.2\right]$ | $\left[900,1500\right]$ | $\left[0.1,0.42\right]$ | $\left[900,1500\right]$ | [67] | |
3000 | $T\to {tH}\to {l}^{+}\nu {{bl}}^{+}\nu {l}^{-}\bar{\nu }$ | $\left[0.06,0.2\right]$ | $\left[900,1500\right]$ | $\left[0.1,0.42\right]$ | $\left[900,1500\right]$ | [68] | |
3TeV CLIC | 5000 | T → W+b → l+νb | $\left[0.15,0.5\right]$ | $\left[1500,2650\right]$ | $\left[0.24,0.5\right]$ | $\left[1500,2450\right]$ | [37] |
5000 | T → tZ → bjjl+l− | $\left[0.26,0.5\right]$ | $\left[1300,2320\right]$ | $\left[0.4,0.5\right]$ | $\left[1300,1850\right]$ | [66] | |
5000 | $T\to {tZ}\to {bjj}\nu \bar{\nu }$ | $\left[0.21,0.5\right]$ | $\left[1300,2400\right]$ | $\left[0.35,0.5\right]$ | $\left[1300,2000\right]$ | [66] | |
5000 | T → W+b → jjb(l+νb) | $\left[0.05,0.23\right]$ | $\left[1270,1600\right]$ | $\left[0.05,0.23\right]$ | $\left[1270,1500\right]$ | this work |