Higgs production with forward protons Pomwig v2.0 Manchester, Dec. 2003

1
Higgs production with forward protonsPomwig
v2.0Manchester, Dec. 2003
M.Boonekamp, T.Kucs

• Pomwig
• New extensions
• Towards a physics case for DPE
• Future additions

2
Situation

• Process studied since beginning of 90s many
  groups, many models (some of them complementary,
  e.g. inc?exc), large variety of predictions
• Meanwhile much experimental interest, since it
  was realized (Albrow, Rostovtsev) that Missing
  Mass measurements would provide extraordinary
  mass resolution at the Tevatron. LHC study
  performed since then
• (Finland group)
• Forward proton detector setup
• complicated interplay
• 3-4 more years before LHC start-up
• Physics case still to be made
• Given (Tevatron data)
• if (Exc IsLargeEnough) return 0
• else if (Inc IsLargeEnough) return 0
• else return 1
• Very few Monte-Carlo programs Pomwig (?
  Herwig), SCI (? Pythia)

x1
Triggerable
sM
x1 M2/(x2s)
x2
3
Models
QCD, Exclusive
QCD, Inclusive, Non Factorized
p
p
A)
B)
X
X
p
p
QED, Exclusive
QCD, Inclusive, Factorized
p
p,A
D)
C)
X
X
p
p,A
4
Models A
X

• Topology
• 2 outgoing protons hard central system large
  rapidity gaps QCD mediated
• A few hints on phenomenology
• Process is hypothetical but a potential jackpot
  wide range of predictions
• Model A-1 Bialas-Landshoff (Regge-inspired,
  non-perturbative) sH 100 fb (disf.)
• Model A-2 Khoze, Martin, Ryskin (Entirely
  perturbative) sH 3 fb
• Experimental remarks (relevant for LHC)
• H mass range bounded by xminxmins
• Mass resolution down to 1 ( ? Helsinki best
  case)
• s/b H ? bb / bb continuum O(1), thanks to
  several suppression mechanisms (central
  system has Jz0, is color singlet)

5
Models BC
X
X

• Topology
• 2 outgoing protons hard central system
  Pomeron remnants
• Small, very forward (undetectable, if mX large)
  rapidity gaps
• A few hints on phenomenology
• Process exists ( ? is being measured) and is
  fairly large sH 100-300 fb
• Model B Boonekamp-Peschanski-Royon, extension
  of the original (exclusive) Bialas-Landshoff
  model.
• Model C Cox-Forshaw factorization assumes Hera
  fluxes (?Pomwig)
• Experimental remarks (relevant for LHC)
• Can go below xminxmins window to low Higgs
  masses at LHC?
• Any improved mass reconstruction relies on
  Pomeron remnants detection
• s/b H ? bb / bb continuum O(10-3-10-4)
• H ? tt / tt continuum O(10-1-1)

6
Models D
X

• Topology
• 2 outgoing protons a hard central system QED
  mediated
• Summary on phenomenology
• Process exists, is small in pp (sH 0.3 fb)
• large in e.g. Ca-Ca (sH 10 pb), Pb-Pb
  (sH 100 pb)
• Model D-1 pp usual proton EM form factor
  b-space
• (Papageorgiu, Cahn-Jackson)
• Model D-2 AA, Gaussian form factor
  (Cahn-Jackson, Dress-Ellis-Zeppenfeld)
• Remarks
• H mass range bounded by xminxmins in pp
• No proton tagging in heavy-ion collisions
• D-1 long term spin-parity determination?
• D-2 Luminosity too small for Lead-Lead,
  possible try in Ca-Ca mode
• s/b as in A), O(1)

7
Pomwig

• Very few models have a Monte-Carlo incarnation
• (only the Factorized Inclusive, and Soft Color
  Interaction models as far as I know)
• Pomwig v.1 extension to Herwig, by Cox
  Forshaw (model B). Uses
• by a proper reweighting of the photon flux, and
  an adapted choice of the structure functions
• Single Double Diffraction

e

to simulate
e-
8
Pomwig v2.0

• It turns out that the factorized ee- ? ee-
  hadrons machinery of Herwig can be used to
  parametrize a lot of models, including the
  non-factorizable ones
• We generalized the approach to our model (model
  B)
• Other additions
• Exclusive DPE à la Bialas-Landshoff (model A)
• QED diffraction as well (proton-proton and
  heavy-ion mode models D)
• Profits from the many hard subprocesses available
  via Herwig
• New processes gg ? H Jz0 gg ? qq, gg ? gg,
  gg ? qq
• Will appear soon on hep-ph (note/manual) and
  pomwig.com (source code)

9
Pomwig v.2
p-induced P (R) flux
p-induced g flux

Ca-induced g flux

• Regge parameters (P/R trajectories)
• tunable
• g fluxes Z, A, bmin settable

10
Pomwig v.2 dijets
(pTgt20 GeV)
BPR all
BPR bb

BL bb

• Caveat does not contain factor 4 enhancement
  from comparison to CDF Run1 DPE dijets

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Pomwig v2.0 Higgs bosons

BL
BPR
DPE

CF
Papageorgiu
gg

• Caveat does not contain factor 4 enhancement
  from comparison to CDF Run1 DPE dijets

12
Pomwig v2.0 Settings
gg / gg
Model
Process
13
Pomwig v2.0 Perspectives

• Important KMR model missing
• Not so trivial one (numerical) QT integration
  at every phase space point
• First order approx use rescaled BL prediction
  (but x dependence?)
• gg ? ?c, ?b process and interface to exclusive
  inclusive production

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Studies to be performed (? Physics case)

• Inclusive models Determination of Regge
  parameters
• on forthcoming Run2 CDF and D0 data
• ? Predictions at the LHC does any
• channel have a chance (tt? low mass?)
• Exclusive models perform analysis at
• hadron/detector level
• Take background from Inclusive
• production as found above
• Exclusive tt channel (lepton/hadron trigger)
• Worst case exclusive given by gg exchange
• ? do we still see something? (surely no
• discovery, maybe spin/parity in the long term?)
• L1 trigger with central detectors large gaps
• can save us find Lopt, and request it

L s
.P(1 int)
Lopt few 1033?
L