IIT-HEP-10-6 New Experiments with Antiprotons Daniel M. Kaplan∗†‡ IllinoisInstituteofTechnology 1 1 E-mail: [email protected] 0 2 Fermilaboperatestheworld’smostintenseantiprotonsource. Newlyproposedexperimentscan n use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron a J Colliderfinishes. Forexample,theannihilationof8GeVantiprotonsisexpectedtoyieldworld- 6 leading sensitivities to hyperon rare decays and CP violation. It could also provide the world’s ] mostintensesourceoftaggedD0mesons,andthusthebestnear-termopportunitytostudycharm x e mixing and, via CP violation, to search for new physics. Other precision measurements that - p could be made include properties of the X(3872) and the charmonium system. An experiment e using a Penning trap and an atom interferometer could make the world’s first measurement of h [ thegravitationalforceonantimatter. Theseandotherpotentialmeasurementsusingantiprotons couldleadtoabroadphysicsprogramatFermilabinthepost-Tevatronera. 1 v 3 1 3 1 . 1 0 35thInternationalConferenceofHighEnergyPhysics 1 1 July22-28,2010 : Paris,France v i X r ∗Speaker. a †FortheFermilabpbarCollaboration: Arizona: A.Cronin; BartoszekEngineering,L.Bartoszek; UCRiverside: A.P.Mills,Jr.;Cassino:G.M.Piacentino;Duke:T.J.Phillips;FNAL:G.Apollinari,D.R.Broemmelsiek,B.C.Brown, C.N.Brown,D.C.Christian,P.Derwent,M.Fischler,K.Gollwitzer,A.Hahn,V.Papadimitriou,G.Stancari,M.Stan- cari,R.Stefanski,J.Volk,S.Werkema,W.Wester,H.B.White,G.P.Yeh;Ferrara: W.Baldini;FirstPointScientific: R.G. Greaves; Hbar Tech.: S.D. Howe, G.P. Jackson, R. Lewis, J.M. Zlotnicki; Houston: K. Lau; IIT Chicago: D.M.Kaplan,T.J.Roberts,J.Terry,Y.Torun,C.G.White;IITHyderabad,A.Giri;ITEPMoscow:A.Drutskoy;KSU: G.A. Horton-Smith, B. Ratra; KyungPook: H.K. Park; Lebedev: O. Piskunova; Longwood: T. Holmstrom; Luther Coll.: T.K.Pedlar;Michigan: H.R.Gustafson;MoscowState: M.Merkin;NASAMarshall: J.B.Pearson;Northwest- ern: J.Rosen;NotreDame: M.Wayne;Oxford: F.Azfar;SMU:T.Coan;St.Xavier: A.Chakravorty;Texas(Austin): M.G.Raizen;Virginia:E.C.Dukes. ‡WorksupportedbytheU.S.Dept.ofEnergy. (cid:13)c Copyrightownedbytheauthor(s)underthetermsoftheCreativeCommonsAttribution-NonCommercial-ShareAlikeLicence. http://pos.sissa.it/ NewExperimentswithAntiprotons DanielM.Kaplan 1. Medium-EnergyAntiprotonExperiment Hyperon and charm CP violation provide windows into physics beyond the Standard Model thatarecomplementarytothoseintheBandK sectors[1,2]. Withsubstantialexpectedcharmand hyperon production and low backgrounds, medium-energy antiproton annihilation can potentially yield event samples large enough to reveal effects of new physics that may have been missed in previous studies.1 A very capable experiment for such studies can be mounted inexpensively at theFermilabAntiprotonAccumulator,byaddingamagneticspectrometertotheexistingFermilab E760lead-glasscalorimeter[3],usinganavailableBESSsolenoid[4],fine-pitchscintillatingfibers (SciFi), the DØ SciFi readout system [5], and hadron ID via fast timing [6]. If the relevant cross sections are as large as expected, this apparatus could enable world-leading studies of hyperon andcharmCPviolationandraredecays,charmmixing,andX(3872)properties,alongwiththose of other charmonium and nearby states, as is now proposed to Fermilab [7]. If approved, the experimentcouldstartaboutayearaftercompletionoftheTevatronColliderrun. Charm D0–D0 mixing is now established at >10 standard deviations [8], but the <1% values ∼ of the reduced mixing parameters x and y are small enough to be possible Standard Model ef- fects [1]; the “smoking gun” for new physics in charm mixing will thus be CP violation [1, 9]. Unlikethebeautyandkaoncases,StandardModeleffectsincharmarehighlysuppressed,offering alow-backgroundvenuefornew-physicsstudies;moreover,someclassesofnewphysicscouldbe inherently more visible in interactions of “up-type” rather than “down-type” quarks. The annihi- lationof8GeVantiprotonswithnucleonsinafixedtargetoffersacharmcrosssectionpotentially of order microbarns, 103 times larger than that at the B factories, along with low combinatoric background,makingitpossiblytheidealwaytosearchfornewphysicsviarareeffectsincharm. Hyperons Having acquired (as of 1999) the world’s largest HEP data sample, the Fermilab Hy- perCPexperiment[10]foundevidence(at<3standarddeviations)fornewphysicsinhyperonCP violationandraredecays[11,12],indicatingtheneedforyetmoredata. Anexperimentdesigned to accomplish the charm studies just discussed can also acquire very large samples of hyperon decaysandpushprecisionhyperonstudiestothenextlevelofsensitivity. X/Y/Z states The B factories discovered new states in the charmonium region, not all of which can be charmonium levels [13]. For example, the width of the puzzling X(3872) resonance (seen infourexperiments)maywellbe(cid:28)1MeV[14]. Theunique ppprecision,reflectingthesmall p- beamδp/pandabsenceofFermimotioninahydrogentarget, isthuswhatisneededtoestablish whetherthisstateisaD∗0D0 molecule[15],atetraquarkstate[16],orsomethingelseentirely. 2. AntihydrogenExperiments In-flightCPTtests Productionofantihydrogeninflight[17]mayofferawayaroundsomeofthe difficultiesencounteredintheCERNAntiprotonDecelerator(AD)trappingexperiments. Methods have been proposed to measure in flight the antihydrogen Lamb shift and fine structure [18]. Use oftheAntiprotonAccumulatorforthispurposemaybecompatiblewithnormalTevatronCollider operations,andtheprogramcouldcontinueintothepost-Tevatronera. 1TheevidenceforanomalousCPviolationinBsmixingrecentlyannouncedbytheDØcollaboration[19],ifcon- firmed,mayindicatethatnewphysicsdoesindeedcontributetoCPasymmetriesatdetectablelevels. 2 NewExperimentswithAntiprotons DanielM.Kaplan AntimatterGravityExperiment WhileGeneralRelativitypredictsidenticalgravitationalforces on matter and antimatter, no direct experimental test has yet been made [20]. Effects of quantum gravity, possible “fifth forces,” non-1/r2 dependence, Lorentz violation [21], etc. can show up in such tests, now approved at the AD [22] and proposed at Fermilab [23]. The latter proposal is to measure a slow (≈1km/s) antihydrogen beam, formed in a Penning trap, using an atom interferometer composed either of material gratings (giving δg/g ∼ 10−4) or laser beams [24] (δg/g∼10−9). Deceleration for trapping can be accomplished down to ≈400MeV in the Main Injector,followedbyan“antiprotonrefrigerator”[25],reverselinac,orsmallsynchrotron[23]. References [1] A.A.Petrov,arXiv:hep-ph/0311371andNucl.Phys.B(Proc.Suppl.)142(2005)333;M.Artuso,G. Buchalla,etal.,Eur.Phys.J.C57,309–492(2008),Sec.3.9. [2] Seee.g.J.Tandean,Phys.Rev.D69,076008(2004). [3] L.Bartoszeketal.,Nucl.Instrum.Meth.A301,47(2006). [4] Y.Makidaetal.,IEEETrans.Appl.Supercond.5,174(1995). [5] V.M.Abazovetal.[DØCollaboration],Nucl.Instrum.Meth.A565(2006)463. [6] Seehttp://psec.uchicago.edu/. [7] T.J.Phillipsetal.,P-986LetterofIntent(2009);seealsohttp://capp.iit.edu/hep/pbar/. [8] Heavy-FlavorAveragingGroup,http://www.slac.stanford.edu/xorg/hfag/charm/. [9] Seee.g.I.I.Bigi,N.Uraltsev,Nucl.Phys.B592(2001)92. [10] R.A.Burnsteinetal.[HyperCPCollaboration],Nucl.Instrum.Meth.A541(2005)516. [11] H.K.Parketal.[HyperCPCollaboration],Phys.Rev.Lett.94,021801(2005). [12] C.Materniak,Nucl.Phys.B(Proc.Suppl.)187(2009)208;E.C.Dukesetal.[HyperCP Collaboration],inpreparation. [13] Seee.g.E.Eichten,K.Lane,andC.Quigg,Phys.Rev.D73,014014(2006). [14] E.Braaten,J.Stapleton,arXiv:0907.3167[hep-ph]. [15] N.A.Tørnqvist,Phys.Lett.B590(2004)209. [16] L.Maiani,F.Piccinini,A.D.Polosa,V.Riquer,Phys.Rev.D71,014028(2005). [17] G.Blanfordetal.,Phys.Rev.Lett.80,3037(1998). [18] G.Blanfordetal.,Phys.Rev.D57,6649(1998). [19] V.M.Abazovetal.[DØCollaboration],Fermilab-Pub-10/114-E,May16,2010. [20] M.Fischler,J.Lykken,T.Roberts,arXiv:0808.3929[hep-th]. [21] V.A.Kostelecký,J.D.Tasson,arXiv:1006.4106[gr-qc]. [22] G.Drobychevetal.,AEGISProposal,CERN-SPSC-2007-017. [23] A.D.Croninetal.,AGELetterofIntent(2009). [24] M.Kasevich,S.Chu,Appl.Phys.B54321(1992). [25] T.J.Roberts,D.M.Kaplan,2009ParticleAcceleratorConference,paperWE6PFP096. 3