Thoughts about tagged neutrino beam, GELATRINO proposal at LHC

Á. Fülöp, Z. Gilián and G. Vesztergombi Roland Eötvös University and KFKI-RMKI, Budapest,

Hungary

Zimányi 2009 WINTER SCHOOL ON HEAVY ION PHYSICS

Nov. 30. - Dec. 4., Budapest, Hungary

GE neva LA ke T agged neu TRINO

OUTLINES

History

FCNC

Detector

Expected rates

Summary

HISTORY

http://www.springerlink.com/content/a63n430lj346487n/

Proposal for UNK, Serpukhov

Z

Unknowns: decay point: ZD and momenta: P,P,P

Decay zone Shielding

XYTER-wall

Unknowns are only the momenta: PK,P,P,P

MAGNET

Decay zone Shielding

XYTER-wallPossible e,identification

Estimate: 105 ev/year

http://accelconf.web.cern.ch/AccelConf/e96/abstracts/ass407a.pdf

FCNC

In theoretical physics, flavor changing neutral currents (FCNCs) are expressions that change the flavor of a fermion current without altering its electric charge. If they occur in the Lagrangian, they may induce processes that have not been observed in experiment. Flavor changing neutral currents may occur in the Standard Model beyond the tree level, but they are highly suppressed (the GIM mechanism).

Wikipedia: Flavor_changing_neutral_current

FCNCs are generically predicted by theories that attempt to go beyond the Standard Model, such as the models of supersymmetry or technicolor. Their suppression is necessary for an agreement with observations, making FCNCs important in model-building.Experiments tend to focus on flavor changing neutral currents as opposed to flavor changing charged currents, because the weak neutral current (Z boson) does not change flavor in the Standard Model proper at the tree level whereas the weak charged currents (W bosons) do. New physics in charged current events would be swamped by more numerous W boson interactions; new physics in the neutral current would not be masked by a large effect due to ordinary Standard Model physics.

Above: Highly suppressed tau lepton decay via flavor-changing neutral current at one-loop order in the Standard Model.

Below: Beyond-the-Standard Model tau lepton decay via flavor-changing neutral current mediated by a new S boson.

Credit: Saul Cohen

Consider a toy theory in which a new boson S may couple both to the electron as well as the tau lepton via the term

        The electric charge of S clearly must vanish, since the electron and tau have equal charge. A Feynman diagram with S as the intermediate particle is able to convert a tauon into an electron (plus some neutral decay products of the S). The MEG experiment in Zurich will search for a similar process, in which an antimuon decays to a photon and a positron. In the Standard Model, such a process proceeds only by emission and re-absorption of a charged W boson, which changes the tau into a neutrino and then an electron, emitting a photon to conserve energy and momentum.In most cases of interest, the boson involved is not a new boson S but the Z boson itself (FCNCs involving the photon can't occur at zero momentum transfers because of the unbroken electromagnetic gauge symmetry; as such, FCNCs involving the photon at a nonzero momentum transfer are relatively suppressed compared to FCNCs involving the Z boson). This can occur if the coupling to weak neutral coupling is (slightly) nonuniversal. The dominant universal coupling to the Z boson does not change flavor, but subdominant nonuniversal contributions can.

Above: Highly suppressed tau lepton decay via flavor-changing neutral current at one-loop order in the Standard Model.

Below: Beyond-the-Standard Model tau lepton decay via flavor-changing neutral current mediated by a new S boson.

Credit: Saul Cohen

Present proposal: electron muon

DETECTOR

DETNI-A DETNI-A 157157Gd/Si Detector ModuleGd/Si Detector Module

slide courtesy C.J.Schmidt

100 mm

GoalsGoals• 108 n/sec in 100 cm2

• with 2 views, 2 hit/strip:400 MHz strip hit rate

• with 5 Byte/hit:2 GByte/sec data

ConsequenceConsequencess

• 128 channel ASIC• 20 chip/module• 20 MHz/chip• 100 MByte/chip

N-XYTER Block Schematic

• Measurement of time, energy and position• Data acquisition speed ~ 1Gbps• Input Clock ~ 250MHz• Input channels ~ 1024 or higher• Data - 8-bit parallel after flash ADC• ADC – Flash type 8-bit (MAX-106 600MSPS)• Time stamp, channel-ID and status signals 32 bit(8-bit parallel x 4

packet)

Understanding Data Acquisition System for N-XYTER

www.gsi.de/documents/DOC-2007-Aug-28-2.ppt

RATES

L. Nodulman’s estimate: 105 tagged neutrino events/year

GELATRINO has 1000 times larger detector material !!!!

SIGNATURA: single muon track with exactly known energy = RANGE

At this preliminary stage it is hard to present precise numbers about the number of -e elastic scattering events, but one can be sure

that it should be many thousand times higher than in the CHARM-II experiment.

SummaryIt is demonstrated that using Lake Geneva as target for high energy neutrinos

originating from K0L decays produced in 7 TeV proton-nucleus interactions one can measure large number of tagged -e interactions. Though one can reach

considerable improvements compared to previous experiments, it remains open whether this will be enough to discover FCNC.

More experimental and theoretical work is required. One should remark, however, that the tagging facility itself

could be a gold-mine for the study of rare neutral kaon decays.

Acknowledgement We wish to thank D. Nanopoulos and M. Mangano for enlightening comments

on the present topic.

END

FCNCs involving the Z boson for the down-type quarks at zero momentum transfer are usually parameterized by the effective action term

                               This particular example of FCNC is often studied the most because we have some fairly strong constraints coming from the decay of B0 mesons in Belle and BaBar. The off-diagonal entries of U parameterizes the FCNCs and current constraints restrict them to be less than one part in a thousand for |Ubs|. The contribution coming from the one-loop SM corrections are actually dominant, but the experiments are precise enough to measure slight deviations from the SM prediction.FCNCs are generically predicted by theories that attempt to go beyond the Standard Model, such as the models of supersymmetry or technicolor. Their suppression is necessary for an agreement with observations, making FCNCs important in model-building.Experiments tend to focus on flavor changing neutral currents as opposed to flavor changing charged currents, because the weak neutral current (Z boson) does not change flavor in the Standard Model proper at the tree level whereas the weak charged currents (W bosons) do. New physics in charged current events would be swamped by more numerous W boson interactions; new physics in the neutral current would not be masked by a large effect due to ordinary Standard Model physics.