LHC AFTER THE CHAMPAGNE

1

• LHC AFTER THE CHAMPAGNE
• Gordy Kane, Aspen, August 2005
• Goals
• Obstacles
• LHC Olympics, results from first LHC run
• CPV at LHC
• Techniques under study to overcome obstacles

2

• WHAT MIGHT WE LEARN FROM LHC?
• Everyone here expects LHC (detectors) to discover
  data relevant to learning how the EW SU(2)xU(1)
  symmetry is broken
• Lets assume what is discovered is evidence for
  supersymmetry if not, similar issues arise
• First, find signals not consistent with the SM,
  celebrate discovery
• Everyone wants to interpret data to learn about
• ? Really supersymmetry? There are some tests.
• ? Spectrum of superpartners?
• ? EWSB?
• ? The parameters of the low scale susy
  Lagrangian, particularly the soft-breaking
  Lagrangian
• ? MSSM a good description? EMSSM?
• ? How is susy broken?
• ? LSPDM?
• ? Underlying high scale theory?

3

• BUT WHAT IS REALLY REPORTED BY THE DETECTORS?
• ? X BR for various inclusive signatures
• e.g. number of events with same sign leptons,
  2 or more jets (with Ejet gt 100 GeV) missing
  transverse energy gt 100 GeV
• Some kinematical distributions
• THATS ALL
• -- Not superpartner masses generally not
  measurable
• -- Not Lagrangian parameters
• SO HOW CAN WE ANSWER THOSE QUESTIONS?
• An inclusive signature is anything that is
  really measurable at a hadron collider. Use all
  information.

4

• Dont know the theory describing what is
  discovered
• If susy, useful to discuss in general MSSM
• --MSSMSM superpartners 3-2-1 2 Higgs
  doublets R-parity
• Correct low scale theory might be EMSSM
• -- common in string based models, e.g. extra
  low scale U(1) with associated Z?
• But such extensions contain MSSM, so useful to
  work in that framework
• (see recent work of Barger, Langacker et al for
  some EMSSM phenomenology)
• In MSSM 15-20 parameters could have significant
  effect on inclusive signatures at hadron
  colliders
• Gaugino masses M1, M2 , M3, all complex
• b, µ complex, tanß
• Sfermion masses, trilinears
• Stop, sbottom lighter?
• Slepton squark? LR?

5

• Does MSSM have a lot of parameters?
• -- supersymmetry means the supersymmetric
  Standard Model
• parameters determined by the symmetry except
  the ratio of higgs vevs and masses (or parameters
  with dimensions of mass), because no masses can
  be determined from first principles yet
• seems like a lot because masses can be
  complex, and because flavor eigenstates may not
  be mass eigenstates in SM all quark masses and
  the CKM matrix had to be measured would be good
  to measure masses here too
• -- but note -- didnt need to measure them to
  learn the SM theory perhaps similar here

6

• For over a decade after initial LHC data will
  have only hadron collider(s) --- (plus clues from
  DM, gµ-2, EDMs and even theory) so try to
  answer all the questions with guidance from the
  data we will have
• BUT THERE ARE MAJOR OBSTACLES TO INTERPRETING
  DATA AT A HADRON COLLIDER
• Only discuss obstacles beyond understanding SM
  data, even though that is the most important
  issue
• In general there are more parameters that affect
  observables than independent observables (so it
  would have been good to have a linear collider),
  in two senses
• -- even if it were possible to measure masses
  of mass eigenstates cannot invert to get
  Lagrangian parameters
• -- parameters that give a particular signature
  not unique
• Most particle masses arise from mass matrices,
  related to Lagrangian parameters in complicated
  way need to deduce Lagrangian parameters

7

• Example of first sense consider charginos
• Four unknowns, two observablescant invert even
  if could measure chargino masses!
• Doesnt converge if add cross section, BR info
• Masses, cross sections depend on phases (not only
  CPV)
• In general, more independent parameters than
  useful observables at hadron collider

8

• Higgs sector if Mh 115 GeV need large loop
  contribution to mass since tree level maximum is
  MZ.
• Then at least 7 parameters enter higgs sector,
  and affect cross section, BR, etc.
• Also, often in models decays to superpartners
  occur for heavy higgs, and sometimes even for h.
• Essentially no study so far of this sector
  realistically some parameter overlap with
  chargino, neutralino sectors

9

• One way to do better -- could be lucky, e.g.
• B?µµ at Tevatron or LHC would imply large tanß
• Light stop
• Some fortunate people who know some parameters
  (i.e. know many relations and values among the
  MSSM parameters) have fewer parameters to measure
  than the rest of us
• E.g. mSUGRA (4 real parameters)
• If mSUGRA fits the data is it the right answer,
  or can many other models also fit the data?
• TALK TOMORROW Liantao Wang (Arkani-Hamed, Kane,
  Thaler, Wang, in preparation) consider MSSM
  parameter space and signature space -- at hadron
  collider many regions in parameter space give
  same signature problem quantified

10

• -- Simulate many MSSMs, different parameters
• -- Define distance in parameter space and
  distance in signature space 22 inclusive
  signatures
• -- Would like to have small distance in
  parameter space lead to small distance in
  signature space and conversely
• -- No --

11

• LHC OLYMPICS
• Motivated by general excitement about LHC coming,
  and by desire to understand better how to deal
  with such issues, some theorists want to practice
  with example(s) ? set up blackbox model(s) and
  begin to work on how to interpret possible data
• Google lhc olympics go to website -- links to
  results from LHC first run presented two ways
  we thought maybe some people would like to
  analyze data in form experimenters get it now
  data also in inclusive signature form for
  excesses beyond SM just as it would be reported
  at first meeting, so theorists or anyone who
  wants can try to figure out spectrum, underlying
  theory
• Meeting at CERN, June 25,26, went well, 60-80
  people, about 25 theorists, lots of discussion
• No one in charge current workers Antoniadis,
  Arkani-Hamed, Dimopoulos, Giudice, Kane, Lykken,
  Mrenna, Shiu, Strassler, Verlinde whoever
  thinks such activities important and wants to
  help make them happen

12

• PROGRAM
• June 25
• GK, Introduction and highlights of the first LHC
  year
• Jesse Thaler, From LHC Signatures to Models
• Discussion
• Lunch
• Matt Strassler, A model-independent approach to
  the LHC Olympics data
• Piyush Kumar, A collider physics primer for
  beginners
• June 26
• Nima Arkani-Hamed, Highlights from the LHC first
  year prime
• Piyush Kumar, The mSUGRA footprint in signature
  space
• Discussion
• Lunch
• Albert de Roeck, LHC physics for this meeting,
  data challenges, connecting theory and data
• Final discussion

13

• for me the goals are to bring in other theorists
  who might not work on understanding LHC data, by
  providing an example of what might be reported at
  the first meeting, so they can think about
  whether they want to learn what is needed to
  analyze data or test their models, and perhaps
  to help expert phenomenologists see that
  overcoming the obstacles will require new
  techniques (which can be developed before the
  data)
• I hope some experimenters and theorists also try
  to go from detector output to inclusive
  signatures not much successful activity in this
  area so far
• Website also has a link to an initial draft of a
  beginners Primer, so people without experience
  can learn how to begin using software like
  Comphep, Pythia, etc to convert a theory into a
  spectrum, decay BR, and signatures lower the
  barriers to using nice software

14

• Now turn to some signals from current blackbox
  model, for 2 fb-1 -- this is what might be
  reported at first conference after turnon

15

• Cuts
• ???lt 3
• R0.52
• Missing ET, Jet ET gt 100 GeV
• Leptons e or µ with ???lt3 and pT gt20 GeV
• Leptons isolated with activity in R0.3 cone lt 5
  GeV
• Initial and final state radiation included
• 73K events (simulated in pythia, no SM)
• At this level assume signals are above the SM
  backgrounds goal is to think about
  interpreting this BTSM physics, find a spectrum
  of particles it arises from, find a theory that
  might imply it could also look at data with SM
  background and try to produce this table, graphs

16
(No Transcript)
17

• N jets 0 1 2 3 gt3
• Leptons
• 0 2919 10284 10694 6857
  4734
• 1 607 1693 1458 760
  411
• SS 15 49
  25 9 5
• OS 27 35
  25 7 6
• trileptons 0
  0 0 0 0
• (Number of jets in each category depends on cuts,
  etc)

18

• From such results is it supersymmetry that is
  discovered? What are the superpartner masses and
  the low scale Lagrangian? How is the EW symmetry
  broken? How is supersymmetry broken? What is the
  underlying 4D string theory? What is the 10D
  string theory?

19

• Briefly consider techniques to learn about the
  underlying theory
• So far focused on problems, obstacles to
  measuring the desired new particle masses and
  properties, to deducing the low scale spectrum,
  or low scale Lagrangian
• Will it be like fermion masses, where have all
  the data but no consensus on implications????
• Actually here situation is less bad than it might
  have been, and we can see ways to try to make
  progress
• Working on ways using only inclusive signatures
  to test gaugino mass unification (even though
  cant measure individual gaugino masses),
  ordering of masses, composition of LSP, etc.,
  maybe even measure tanß
• Needs considerable input by theorists as well as
  experimenters even more than LEP

20

• What was learned from LEP? Basically 3 things
• Gauge coupling unification
• Global fit implies upper limit on higgs boson
  mass
• No deviations from SM numbers implies weakly
  coupled extension
• (plus, N?2.981-0.008)
• -- All required major interaction of experiment
  and theory none could be learned from data
  alone
• (All suggest supersymmetric SM)

21

• Constraints from top-down analysis, from relating
  observables will be very powerful stringy
  theories not yet able to make convincing low
  scale predictions, but such predictions may be
  suggestive of what to expect

22
PATTERNS OF INCLUSIVE SIGNATURES CAN POINT TO
UNDERLYING THEORY(all events have 2 or more
energetic jets and large missing transverse
energy)
23

• No single signature will distinguish, but pattern
  is very powerful
• Also learning how to look at footprints of a
  theory in inclusive signature space does not
  fill space any data point outside any footprint
  excludes theory
• In general working in signature space a powerful
  tool to study theories, phenomenology needs
  much more study

24
(No Transcript)
25

• CPV at LHC
• One reason number of mass parameters larger is
  that masses can be complex if so it affects not
  only CPV but cross sections, decay BR, LSP relic
  density, etc
• Phases (small or large) may be very important as
  clues to how supersymmetry is broken, to the
  underlying theory, to baryogenesis
• Studies significantly hampered by lack of
  simulation programs that properly include full
  effects of complex masses (theory fully
  summarized in review, Chung et al,
  hep-ph/0312378)

26

• EDMs give a few constraints on phases,
  b-factories may
• To know what is happening must study CPV at LHC
  not hard in principle
• Not a problem that start with pp rather than CP
  eigenstate not a problem that detectors not CP
  neutral just look for deviation from SM
  simulation some studies for hadron colliders
  already in toy susy (GK, Mrenna, L-T Wang) new
  studies underway (GK, T-T Wang.)
• It will be possible to use light quark jet
  charges to greatly increase statistics of such
  studies

27

• I conclude LHC data is likely to point the way
  toward achieving our goals, including identifying
  the underlying physics measuring the masses
  great if possible but is not the only way to
  make progress
• Lots of work, and new techniques, needed to make
  progress theorists not well prepared to learn
  from LHC data
• Practicing with blackbox models a very good way
  to make progress
• (-- even for experimenters-- simulated situation
  easier than real if you cant find signals
  present in simulated data unlikely to find them
  in real data if you find non-existent signals
  in simulation likely to find non-existent ones in
  real data)

28

• Next Olympics meeting, CERN, probably Jan 9-10
• -- report spectrum (if any) and underlying
  theory of original blackbox model
• Hopefully by then more people will have found
  signals in blackbox model(s) and will report on
  them
• Hopefully some people will try to deduce the
  spectrum of new particles in the data (if any)
  and will report on them opportunity for good
  phenomenologists
• Hopefully some people will have tried to learn
  the underlying theory of any new physics in the
  data and will report that

29

• SSC Reunion July 23, 2005, Red Oak, TX
• Memorabilia can be viewed throughout the event.
  Some of the things we have for you are
• --A couple of rocks from 230 feet down in the
  tunnel
• --A wide assortment of shirts from Texas to
  Paris, France
• --Magnet cookies
• --All kinds of posters
• --SSC jewelry, SSC watch, SSC buttons, SSC
  coffee mugs, SSC Ellis county maps
• --SSC photo slideshow and videos will be running
  throughout the evening
• Barbecue dinner, provided by BubbaQ's in Red
  Oak, will be served at 6 pm followed by a few
  words from our leader, Roy Schwitters.

30

• Archarya
• Antoniadis
• Arkani-Hamed
• Delgado
• Dimopoulos
• Dudas
• Ghilencea
• Giudice
• Ibanez
• Kane
• Kiritsis
• Kumar
• Langacker
• Luty
• March-Russell
• Nelson
• Nelson
• Ross
• Schmaltz

31

• LIGHTEST HIGGS BOSON
• Probably will take longer than new physics signal
• EWSB conditions MSSM no fine tuning ? mh lt
  100 GeV
• -- still possible, LEP limit 114 GeV not
  applicable for susy higgs
• MSSM ? mh lt 135 GeV
• EMSSM ? mh lt 200 GeV, assuming theory
  perturbative up to of order unification scale

32
(No Transcript)