# lhcb hera mcnulty 2014. 11. 14.¢ R. McNulty, Results from LHCb and their relation with...

date post

01-Feb-2021Category

## Documents

view

1download

0

Embed Size (px)

### Transcript of lhcb hera mcnulty 2014. 11. 14.¢ R. McNulty, Results from LHCb and their relation with...

Results from LHCb and their relation with HERA data

Ronan McNulty (UCD Dublin) on behalf of the LHCb collaboration

Future Physics with HERA Data for Current and Planned Experiments

11-13 November 2014 DESY Hamburg

1

Outline • Introduction: (x,Q2) Rapidity Plane

• PDFs • Z->µµ, Z->ee, Z+jets • W->µν • Effect of LHCb data on HERA derived PDFs

• Diffraction: Central Exclusive Production • Photoproduction • Double pomeron exchange

R. McNulty, Results from LHCb and their relation with HERA 2

J ψ χc J ψ J ψ

The LHCb detector

(some sensitivity -3.5

R. McNulty, Results from LHCb and their relation with HERA 4

Scatters at LHCb are between one high-x and one low-x parton. One region overlaps strongly with HERA. One region is either unexplored or requires large DGLAP evolution from HERA.

R. McNulty, Results from LHCb and their relation with HERA 5

W,Z bosons x~0.5 x~10-3

R. McNulty, Results from LHCb and their relation with HERA 6

J/ψ, χc x~10-5 x~10-2

Z->µµ Z->ee

R. McNulty, Results from LHCb and their relation with HERA 7

Purity of Z->µµ > 99% Purity of Z->ee ~95%

µµ

ee

LHCb-CONF-2013-007

JHEP 02 (2013) 106

Z->µµ Z->ee rapidity and PDF dependence

R. McNulty, Results from LHCb and their relation with HERA 8

Z->ee Z->µµ

LHCb-CONF-2013-007 JHEP 02 (2013) 106

Z+jets, Z+b, (Future: Z+c, W+b, W+c)

R. McNulty, Results from LHCb and their relation with HERA 9

Z+b arXiv:1411.1264

Z+jets JHEP 01(2014) 033

W->µν

R. McNulty, Results from LHCb and their relation with HERA 10

arXiv: 1408.4354

Purity from 30-90% depending on muon pT

arXiv: 1408.4354

W->µν (integrated) & dependence on PDFs

R. McNulty, Results from LHCb and their relation with HERA 11

Slope−1 :σ (W + )

σ (W − ) ≈ du ud

= u d

arXiv: 1408.4354

W->µν (differential) & dependence on PDFs

R. McNulty, Results from LHCb and their relation with HERA 12

arXiv: 1408.4354

W->µν (differential) & dependence on PDFs

R. McNulty, Results from LHCb and their relation with HERA 13

Measure of u/d ratio at different x Sub 1% precision on experimental ratio

arXiv: 1408.4354

Effect of 37pb-1 of LHCb data on HERA-derived PDFs

R. McNulty, Results from LHCb and their relation with HERA 14

Improvement in u quark at high-x. Improvement in d quark at low-x. Sensitivity outside W,Z x-regions through sum-rule constraints.

W 2011

Effect of 1fb-1 of LHCb W data on LHC-derived PDFs

R. McNulty, Results from LHCb and their relation with HERA 15

LHCb has impact at high and low x.

Central Exclusive Production with Dimuon final states

QED Photo production Double pomeron exchange

(Note: J/ψ→µµ and χc→J/ψγ)

Related phenomena where the colourless object creates a particle

R. McNulty, Results from LHCb and their relation with HERA 16

Cross-section proportional to gluon2 and so

Photo-production cross-section

σ ~ (xg)2

σ ~ xλ

R. McNulty, Results from LHCb and their relation with HERA 17

[4]

Note: • • soft/hard • g(x,Q2)

HERA vector meson photo-production results

R. McNulty, Results from LHCb and their relation with HERA 18

σ ~ xλ

10.3204/DESY-PROC-2012-03/58

Sensitivity to gluon pdf

10-6 LHCb LHCb

R. McNulty, Results from LHCb and their relation with HERA 19

Gluon may rise faster than described in global PDFs.

=> Much larger cross- sections for CEP channels

Jones, Martin, Ryskin, Teubner, JHEP 1311 (2013) 085

Graphical Representation

Elastic Scattering

Single Diffraction

Double Diffraction

Central Exclusive Production (elastic)

Central Exclusive Production (inelastic)

y=-10 y=-2 y=0 y=2 y=10 Rough LHCb coverage

R. McNulty, Results from LHCb and their relation with HERA 20

VELO sub-detector

R. McNulty, Results from LHCb and their relation with HERA 21

Use of backwards tracks

R. McNulty, Results from LHCb and their relation with HERA 22

Use of backwards tracks

Clearly not

exclusive R. McNulty, Results from LHCb and their relation with HERA 23

Invariant mass of exclusive muon pairs

Distributions not background-subtracted. 55985 J/ψ and 1565 ψ(2s)

R. McNulty, Results from LHCb and their relation with HERA

JPG 41 (2014) 055002

24

Inelastic background

Signal Background

R. McNulty, Results from LHCb and their relation with HERA 25

How to reject what you can’t see? ...Regge theory suggests exponential dependence

dσ dt ~ ebt

Inelastic background J/ψ

HERA measured: bs=4.9 GeV-2 bpd=1.1 GeV-2 LHCb Expect: bs ~ 6 GeV-2 bpd~ 1 GeV-2 LHCb Fit: bs=5.70±0.11 GeV-2 bpd=0.97±0.04 GeV-2

dσ dt ~ ebt

J/ψ

Regge theory:

R. McNulty, Results from LHCb and their relation with HERA 26

Over greater range, H1 require (EPJ C73 (2013) 2466)

JPG 41 (2014) 055002

Inelastic background ψ(2S)

HERA measured: bs=4.2 GeV-2 bpd=0.6 GeV-2 LHCb Expect: bs ~ 5.5 GeV-2 bpd~ 0.6 GeV-2 LHCb Fit: bs=5.1±0.7 GeV-2 bpd=0.8±0.2 GeV-2

dσ dt ~ ebt

ψ(2S)

ψ(2S)

R. McNulty, Results from LHCb and their relation with HERA 27

JPG 41 (2014) 055002

Integrated Cross-sections

R. McNulty, Results from LHCb and their relation with HERA 28

Good agreement with all theory estimates

J/ψ ψ(2S) Cross-section*BR for both muons in pseudorapidity range 2

Differential cross-sections J/ψ and ψ(2S)

NLO agrees better than LO

R. McNulty, Results from LHCb and their relation with HERA 29

JPG 41 (2014) 055002 JPG 41 (2014) 055002

Photo-production cross-section

LHCb measure

Gap Survival

Photon Flux

Photo-production (HERA / fixed target)

HERA measured power-law: Use this for one cross-section on RHS – LHCb measure the other solution

R. McNulty, Results from LHCb and their relation with HERA 30

Ph ot

o- pr

od uc

tio n

cr os

s- se

ct io

n

Deviation from pure power-law. i.e. NLO required or only power-law for W>W0

Measure Plot HERA

R. McNulty, Results from LHCb and their relation with HERA 31

JPG 41 (2014) 055002

Sensitivity to saturation effects

Motyka, Watt: PRD 78, 014023 (2008) Gay Ducati et al., arXiv: 1305.4611

R. McNulty, Results from LHCb and their relation with HERA 32

Ldt = 37pb−1∫

LHCb

Sensitivity to saturation effects: J/ψ ψ(2S)

R. McNulty, Results from LHCb and their relation with HERA 33

JPG 41 (2014) 055002 JPG 41 (2014) 055002

Search for odderon • Motyka, DIS 2008.

R. McNulty, Results from LHCb and their relation with HERA 34

g

Odderon identification requires good modelling of inelastic background

Probing pomerons: J/ψ+J/ψ

R. McNulty, Results from LHCb and their relation with HERA 35

Mass of second muon pair Mass of J/ψ pair

(CEP at LHCb is glue laboratory. Measure χc , meson pairs, low-mass spectroscopy, search for glueballs, odderons etc.)

J.Phys. G41 (2014) 115002 J.Phys. G41 (2014) 115002

Investigate other vector mesons

looks very like

R. McNulty, Results from LHCb and their relation with HERA 36

10.3204/DESY-PROC-2012-03/58

Dimuon Mass Spectrum

demand gap

Factor ~ *100 data now available with 2011+2012 (~3fb-1)

R. McNulty, Results from LHCb and their relation with HERA 37

LHCb-CONF-2011-022

Predictions J/ψ

ϒ

R. McNulty, Results from LHCb and their relation with HERA 38

Jones, Martin, Ryskin, Teubner, JHEP 1311 (2013) 085

High rapidity shower counters for LHCb • Increase rapidity gap with scintillators in forward region • Use existing electronics

R. McNulty, Results from LHCb and their relation with HERA 39

First simulations suggest veto region for charged and neutral particles can be extended to include 5

40

Herschel Integration inside Tunnel

R. McNulty, R