CTEQ TEA PDF Analysis: new experimental data and constraints on new - PowerPoint PPT Presentation

Outline Results From the Global Fits Hadron Colliders CTEQ TEA PDF Analysis: new experimental data and constraints on new physics Marco Guzzi Southern Methodist University, Dallas, TX Pheno 2010 - Univ. of Wisconsin-Madison Based on the papers: 1) New Global PDF Analysis and Light Gluinos: Tools for the LHC -E.Berger, M.G., H.L. Lai, F. Olness and P. Nadolsky- 2)CTEQ 2010 paper Marco Guzzi 1

Outline Results From the Global Fits Hadron Colliders Two questions are addressed in this talk: 1. What is the impact of the combined HERA Run I data on the CTEQ analysis? 2. Can the new data better constrain non-SM physics? Example: -PDF fits with experimental α s constraints. -Constraints on color-octet fermions (SUSY-like gluinos) from the global hadronic data. I will show a selection of figures. Additional figures are in the PDF file as “Backup” slides! Marco Guzzi 2

Outline Results From the Global Fits Hadron Colliders Two questions are addressed in this talk: 1. What is the impact of the combined HERA Run I data on the CTEQ analysis? Marco Guzzi 3

Outline Results From the Global Fits Hadron Colliders Changes in the central Fits: PDF’s Ratio, Q = 2 GeV CT10 PDFs Ratios (New HERA)/(Sep. HERA) Q = 2 GeV g u 1.2 ub d (New HERA)/(Sep. HERA) db c ⇑ small changes in the u and d 1 change in the charm ☞ change in the gluon ☞ 0.8 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 x Figure: PDF Ratios: (CT10 with the new HERA Run I data vs (CT10 with the separate HERA data)) for Q = 2 GeV. Marco Guzzi 4

Outline Results From the Global Fits Hadron Colliders Changes in the central Fits: PDF’s Ratio, Q = 85 GeV CT10 PDFs Ratios (New HERA)/(Sep. HERA) Q = 85 GeV g u 1.2 ub d (New HERA)/(Sep. HERA) db c b 1 0.8 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 x Smaller changes at 85 GeV Marco Guzzi 5

Outline Results From the Global Fits Hadron Colliders New HERA Run-I data: CT10 vs CTEQ6.6. g(x,Q) Q = 2 GeV u(x,Q) Q = 2 GeV 1.6 1.6 CTEQ6.6/CTEQ6.6M CTEQ6.6/CTEQ6.6M CTEQ6.6/CTEQ6.6M, CT10/CTEQ6.6M CT10/CTEQ6.6M CTEQ6.6/CTEQ6.6M, CT10/CTEQ6.6M CT10/CTEQ6.6M 1.4 1.4 1.2 1.2 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x ub(x,Q) Q = 2 GeV c(x,Q) Q = 2 GeV 1.6 1.6 CTEQ6.6/CTEQ6.6M CTEQ6.6/CTEQ6.6M CTEQ6.6/CTEQ6.6M, CT10/CTEQ6.6M CT10/CTEQ6.6M CTEQ6.6/CTEQ6.6M, CT10/CTEQ6.6M CT10/CTEQ6.6M 1.4 1.4 1.2 1.2 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x Marco Guzzi 6

Outline Results From the Global Fits Hadron Colliders The Impact of HERA data on the PDF uncertainty, Gluon g(x,Q) Q = 2 GeV, New HERA data (red), separate HERA data (blue) 1.6 New HERA1 Separ. HERA 1.4 New HERA vs Separ. HERA 1.2 1 0.8 0.6 0.4 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x Figure: Error bands: (red) CT10 new HERA Run I data, (blue) CT10 with the separate HERA data. g ( x ), Q = 2 GeV. Marco Guzzi 7

Outline Results From the Global Fits Hadron Colliders Applications for the Hadron Colliders: 2. Can the global analysis constrain new physics? Consider for instance gluinos from supersymmetry. Marco Guzzi 8

Outline Results From the Global Fits Hadron Colliders Bounds Current bounds: are relatively light, 10-50 GeV depending on how much trust is put in the constraints from LEP events shapes. Can we improve on these? (See also Berger, Nadolsky, Olness and Pumplin PRD71 2004, Bl¨ umlein and Botts PLB325 1994, R¨ uckl and Vogt Z.Phys.64 1994) Marco Guzzi 9

Outline Results From the Global Fits Hadron Colliders Running of α s in SM and SUSY g = 5 , 10 , 25 , 50 GeV m ˜ 0.22 Pure QCD 0.21 0.2 0.19 0.18 5 0.17 ( µ ) 0.16 α s 10 0.15 0.14 25 0.13 50 0.12 0.11 10 100 µ [GeV] The most accurate constraints on α s reside at Q < 10 GeV and Q = M Z . Running of α s from Q = 10 GeV to M Z may reveal non-SM physics. Marco Guzzi 10

Outline Results From the Global Fits Hadron Colliders Running of α s in SM and SUSY m ˜ g = 5 , 10 , 25 , 50 GeV 0.22 Pure QCD 0.21 0.2 0.19 0.18 0.17 5 ( µ ) 0.16 α s 10 0.15 0.14 25 0.13 50 0.12 0.11 10 100 µ [GeV] New feature ⇒ In the fits we have introduced α s ( M Z ) as a fitting parameter. Marco Guzzi 11

Outline Results From the Global Fits Hadron Colliders Running of α s in SM and SUSY g = 5 , 10 , 25 , 50 GeV m ˜ 0.22 Pure QCD 0.21 0.2 0.19 0.18 5 0.17 ( µ ) α s 0.16 10 0.15 0.14 25 0.13 50 0.12 0.11 10 100 µ [GeV] We have included the following data: a) The hadronic data Marco Guzzi 12

Outline Results From the Global Fits Hadron Colliders Running of α s in SM and SUSY g = 5 , 10 , 25 , 50 GeV m ˜ 0.22 Pure QCD 0.21 0.2 0.19 0.18 5 0.17 ( µ ) α s 0.16 10 0.15 0.14 25 0.13 50 0.12 0.11 10 100 µ [GeV] We have included the following data: b) α s ( M Z ) = 0 . 123 ± 0 . 0040 from e + e − hadronic event shapes (see Dissertori et.al. ) Marco Guzzi 13

Outline Results From the Global Fits Hadron Colliders Running of α s in SM and SUSY g = 5 , 10 , 25 , 50 GeV m ˜ 0.22 Pure QCD 0.21 0.2 0.19 0.18 5 0.17 ( µ ) α s 0.16 10 0.15 0.14 25 0.13 50 0.12 0.11 10 100 µ [GeV] We have included the following data: c) a lower- Q composite constraint at Q = 5 GeV α s ( Q ) = 0 . 213 ± 0 . 0022 Marco Guzzi 14

Outline Results From the Global Fits Hadron Colliders Composite α s at Q = 5 GeV α s ( Q = 5 GeV ) = 0 . 213 ± 0 . 002 • Obtained by the combination of α s ( Q = 5) = 0 . 218612 ± 0 . 005757 from τ decay (see Baikov, Chetyrkin, Kuhn PRL101 2008) (1) α s ( Q = 5) = 0 . 21435 ± 0 . 00301 from heavy quarkonia (see Amsler et. al. PLB667 2008 ref. therein) (2) α s ( Q = 5) = 0 . 20897 ± 0 . 003925 from lattice QCD (see Amsler et. al. PLB667 2008) (3) • Evolved to the common scale Q = 5 GeV in pure QCD and added as a weighted mean. Marco Guzzi 15

Outline Results From the Global Fits Hadron Colliders The impact of gluinos on the PDFs: floating α s ( M Z ) g(x,Q) Q = 2 GeV, CT10: red error band g(x,Q) Q = 2 GeV, CT10: red error band 1.6 1.6 m ∼ g = 10 GeV ratio to CT10 m ∼ g = 20 GeV ratio to CT10 1.4 1.4 1.2 1.2 SUSY/CT10M SUSY/CT10M 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x g(x,Q) Q = 2 GeV, CT10: red error band c(x,Q) Q = 2 GeV, CT10: red error band 1.6 1.6 m ∼ g = 50 GeV ratio to CT10 m ∼ g = 50 GeV ratio to CT10 1.4 1.4 1.2 1.2 SUSY/CT10M SUSY/CT10M 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x Marco Guzzi 16

Outline Results From the Global Fits Hadron Colliders The impact of gluinos on the PDFs: α s ( M Z ) = 0 . 118 g(x,Q) Q = 2 GeV, CT10: red error band α s (M Z )=0.118 g(x,Q) Q = 2 GeV, CT10: red error band. α s (M Z )=0.118 1.6 1.6 m ∼ g = 10 GeV ratio to CT10 m ∼ g = 20 GeV ratio to CT10 1.4 1.4 1.2 1.2 SUSY/CT10M SUSY/CT10M 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x g(x,Q) Q = 2 GeV, CT10: red error band. α s (M Z )=0.118 c(x,Q) Q = 2 GeV, CT10: red error band. α s (M Z )=0.118 1.6 1.6 m ∼ g = 50 GeV ratio to CT10 m ∼ g = 50 GeV ratio to CT10 1.4 1.4 1.2 1.2 SUSY/CT10M SUSY/CT10M 1 1 0.8 0.8 0.6 0.6 0.4 0.4 10 -5 10 -4 10 -3 10 -5 10 -4 10 -3 0.01 0.02 0.05 0.1 0.2 0.5 0.9 0.01 0.02 0.05 0.1 0.2 0.5 0.9 x x Marco Guzzi 17

Outline Results From the Global Fits Hadron Colliders ∆ χ 2 as a function of m ˜ g : Floating α s ( M Z ) A fit with a floating α s (M Z ) 200 2010 study 2004 study 0.131 150 100 ∆ χ 2 50 0.128 0.135 0.121 0.118 0 gluino decoupling → 0.127 0.131 -50 0.121 2 5 10 20 30 50 100 200 500 m ∼ g [GeV] m ˜ g < 15 GeV are excluded for all the α s ( M Z ) values. g ≈ 50 GeV results in ∆ χ 2 ≈ − 55 as compared to the pure QCD case m ˜ Marco Guzzi 18

Outline Results From the Global Fits Hadron Colliders ∆ χ 2 as a function of m ˜ g : Fixed α s ( M Z ) = 0 . 118 A fit with a fixed α s (M Z )=0.118 250 2010 study 2004 study 200 150 ∆ χ 2 100 50 0 gluino decoupling → 5 10 20 30 50 100 200 m ∼ g [GeV] m ˜ g < 25 GeV are excluded for the fits with a fixed α s ( M Z ). There is an improvement with respect to the study performed in 2004 Marco Guzzi 19

Outline Results From the Global Fits Hadron Colliders Why are the constraints on gluinos remain weak? • Precise DIS data are at Q < 20 − 30 GeV ⇒ cannot constrain heavier gluinos. • In the jet data, the reduction in the NLO rate due to suppressed gluon PDF is compensated by a larger α s . √ • At the LHC, S = 7 TeV the discovery of gluino-like fermions could be feasible with sufficient control on the systematic uncertainties and with precise measurements of α s . Marco Guzzi 20