W + W - Z 0. Question. From Last Time. Fundamental Matter Particles. The Standard Model. Carriers of the weak force. Ice Cube

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From Last Time Dissse the weak interation All qarks an leptons have a weak harge They interat throgh the weak

Interation with the weak fiel y exiting an exhange oson hanges one partile into another.

Gravitational, Strong, Weak Fri. May 4, 2007 Phy107 Letre 39 3 Fri.

1 From Last Time Dissse the weak interation All qarks an leptons have a weak harge They interat throgh the weak interation Weak interation often swampe y eletromagneti or strong interation. Interation with the weak fiel y exiting an exhange oson hanges one partile into another. Qestion Whih of the following partiles is not a matter partile A. Eletron B. Qark C. Glon D. Netrino Fri. May 4, 2007 Phy107 Letre 39 1 Fri. May 4, 2007 Phy107 Letre 39 2 Fnamental Matter Partiles The Stanar Moel Three generations of leptons an qarks All feel the weak fore. Charge leptons feel weak & EM fores Qarks feel weak, EM, & strong 6 leptons 6 qarks 4 interations Eletromagneti, Gravitational, Strong, Weak Fri. May 4, 2007 Phy107 Letre 39 3 Fri. May 4, 2007 Phy107 Letre 39 4 Carriers of the weak fore Like the Eletromagneti & Strong fores, the Weak fore is also meiate y fore arriers. Ie Ce Netrino telesope, t etets light! A partile with a weak harge an ople to the weak fiel an exite one of these partiles W + W - Z 0 These weak fore arriers arry eletri harge also! This weak fore arrier is eletrially netral Fri. May 4, 2007 Phy107 Letre 39 5 Fri. May 4, 2007 Phy107 Letre

Netrino into mon Qestion n ν µ W + µ - p time Netrino interats with qarks insie nleons in nles. Interation: Netrino emits W +, hanging into mon. Down qark in netron asors W +, hanges to p qark.

2 Netrino into mon Qestion n ν µ W + µ - p time Netrino interats with qarks insie nleons in nles. Interation: Netrino emits W +, hanging into mon. Down qark in netron asors W +, hanges to p qark. Nleon now has 2 ps 1 own, --> a proton! Whih of the following partiles annot interat with a partile that arries only the weak harge? A. Qark B. Netrino C. Eletron D. All of them an Fri. May 4, 2007 Phy107 Letre 39 7 Fri. May 4, 2007 Phy107 Letre 39 8 Qark flavors Eah qark has a ifferent "flavor." For instane, the flavor of an p qark is simply "p. Up qark hanging to own qark is hanging flavor. A generi way of referring to ifferenes etween qarks. Leptons also have a flavor Netrino hanging into a mon is hanging flavor Changing flavors Flavor hange an or spontaneosly. Experimentally, this ors within a lepton generation Generation I e ν e Eletron is stale Generation II µ ν µ 2x10-6 seons Generation III τ ν τ 3x10-13 seons Charge -1 0 Fri. May 4, 2007 Phy107 Letre 39 9 Fri. May 4, 2007 Phy107 Letre Lepton pairs Think of lepton pairs as a single partile with two states. Emitting or asoring W toggles it etween the states. Can say that the W arries away weak harge (also alle flavor harge ) in aition to eletri harge (atally isospin) E.g. when a mon emits a W, this flips the lepton pair into a ifferent orientation, whih we see as a netrino. Get ri of those partiles! This flipping only onsiere in a partilar lepton pair. Other generations separate. Bt experimental eviene for eays etween netrinos in ifferent generations (Netrino osillations) In a nifie theory, all leptons may jst e ifferent states of a single partile! This is appealing sine the only ifferene etween generations is mass. Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre

Matter partiles & fore arriers Matter Partiles Qarks an leptons These are fermions (half-integer spin) Fore paritiles These are all osons (integer spin) Qarks an the weak fore Qarks have olor harge,

3 Matter partiles & fore arriers Matter Partiles Qarks an leptons These are fermions (half-integer spin) Fore paritiles These are all osons (integer spin) Qarks an the weak fore Qarks have olor harge, eletri harge, an weak harge other interations swamp the weak interation Bt similar to leptons, qarks an hange their flavor (eay) via the weak fore, y emitting a W partile. Generation I Generation II Generation III t Charge +2/3 s -1/3 Emit W + 2x10-12 seons Emit W seons Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre Flavor hange etween generations Bt for qarks, not limite to within a generation Similar to leptons, qarks an hange their flavor (eay) via the weak fore, y emitting a W partile. Generation I Generation II s Generation III Fri. May 4, 2007 Phy107 Letre t seons Charge +2/3-1/3 t Deay of heavy qarks τ + ν τ W + W + Top qark eays so fast (10-23 s), it oesn t have time to form a meson. t + t + + n t Fri. May 4, 2007 Phy107 Letre W - µ - ν µ e + ν e s B partile eays within 1.5x10-12 s. B - D 0 + µ - + ν µ The D 0 meson eays within 0.5x10-12 s. This eay: D 0 K - + e - + ν e Top qark isovery 1995 What the etetor sees Proton-antiProton ollision at Fermila Only final eay prots are oserve. Infer existene of other partiles y thinking aot eays. These are the only ojets oserve. Everything else mst e extrapolate. Bil on known reations. Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre

Three generations, six qarks, an e onsiere ifferent faets of same fiel. Why six? This is only an inpt to the theory. Similar partiles All six qarks an hange flavor via the weak interation.

4 Comining the qarks In this sense, ifferent qarks an e onsiere as ifferent manifestations of the same partile. Jst as we woln t all spin-p an spinown eletrons ifferent partiles, the ifferent flavor qarks on t have to e onsiere as ifferent partiles. Three generations, six qarks, an e onsiere ifferent faets of same fiel. Why six? This is only an inpt to the theory. Similar partiles All six qarks an hange flavor via the weak interation. Within a generation or etween generations. Leptons an hange flavor within a generation, an netrinos etween generations(isovere reently y looking at netrinos from the sn). View 12 fnamental matter partiles as only two ifferent types: ifferent flavors are jst iff. orientations. Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre An several ifferent interations Rememer that interations are e to exhange of osons. EM interation - exhange photons Weak interation - exhange W +, W, Z o Strong interation - exhange glons (8) Unifiation Can nify the partiles to some extent (not really aomplishe yet) Bt haven t yet aot nifying the for fores (13 fore-arrying osons) Stanar moel has sessflly nifie two the for fores Eletromagneti an Weak fore nifie into eletroweak. Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre Exhange Bosons (fore arriers) Eletro-weak nifiation EM Weak The stanar moel says that the eletromagneti interation (photon exhange) & the weak interation (W +, W -, Z o exhange) are ifferent piees of the same eletroweak interation Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre

Netral weak Zero harge Mass=91 GeV/ 2 Range ~ 10-18 m Some similarities here Eletromagneti Zero harge Mass=0 GeV/ 2 Range ~ inf.

5 Netral weak Zero harge Mass=91 GeV/ 2 Range ~ m Some similarities here Eletromagneti Zero harge Mass=0 GeV/ 2 Range ~ inf. These two oth exhange netral osons Neither oson hanges the lepton flavor (remains eletron) W + ν ν e W - e νe Pos. weak Pos. harge Mass=80 GeV/ 2 Range ~ m Neg. weak Neg. harge Mass=80 GeV/ 2 Range ~ m These two oth exhange harge osons. Both osons hange the lepton flavor Fri. May 4, 2007 Phy107 Letre ν e Similar inee The Z o an photon interations are so similar that they are very iffilt to istingish experimentally. One of the ieas ehin the Stanar Moel is that partiles physis shol follow reglar an explainale patterns or symmetries. A pattern that wol aont for two hange weak fore arriers also alle for a netral partile: The Z o a netral partile mh like the photon. The Z o was preite y the Stanar Moel, an then fon experimentally. Fri. May 4, 2007 Phy107 Letre Partile mass in the SM The stanar moel has great sesses, t in its first inarnation all partiles were reqire to have zero mass. Otherwise the mathematis gives non-physial reslts. Clearly a major prolem, sine many partiles o have mass. Mass Experimental masses of SM partiles. Original SM gives zero mass for all partiles. Bt an give partiles mass y opling to a new fiel, the Higgs fiel. Higgs oson is the (noserve) qanta of the Higgs fiel. Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre What is mass? Think of inertial mass: inertial mass is a partile s resistane to hanges in veloity. When yo apply the same fore to partiles, the smaller the mass, the larger the aeleration. What is the origin of mass? Mass in the SM In the stanar moel (SM), partiles have mass ease they interat with something that pervaes the niverse. This something is the Higgs fiel Partiles hit the Higgs fiel when yo try to aelerate them Mass = (hane of hit) x (Higgs ensity) Copling onstant Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre

Mass an the Higgs fiel Now a poplar person enters the room, attrating a lster of hangers-on that impee her

spaing. Imagine a party in a room pake fll of people. Nooy is moving aron mh, jst staning an talking.

May 4, 2007 Phy107 Letre 39 31 Low an High Mass In this example, the poplar person plays the role of an

The interation with the Higgs fiel gives the partile its mass A partilarly npoplar person ol move throgh

In present theories, the poplarity of eah partile is an inpt parameter. Fri.

In analogy, sppose an interesting rmor is shote in thr the oor.

The people get qite exite. They lster to pass on the rmor, an the lster propagates thr the room.

poplar person, the lsters also have mass. Fri. May 4, 2007 Phy107 Letre 39 33 A. No mass B.

May 4, 2007 Phy107 Letre 39 34 From the Higgs Boson to Leaelly Physiists from the Lawrene Berkeley

6 Mass an the Higgs fiel Now a poplar person enters the room, attrating a lster of hangers-on that impee her motion As she moves she attrats the people she omes lose to- the ones she has left retrn to their even spaing. Imagine a party in a room pake fll of people. Nooy is moving aron mh, jst staning an talking. Her motion is impee - she has eome more massive. Fri. May 4, 2007 Phy107 Letre Low an High Mass In this example, the poplar person plays the role of an eletron, or a W oson, or any partile. The people in the room represent the Higgs fiel. The interation with the Higgs fiel gives the partile its mass A partilarly npoplar person ol move throgh the room qite easily, with almost no mass. This is the analog of a low-mass partile. In present theories, the poplarity of eah partile is an inpt parameter. Fri. May 4, 2007 Phy107 Letre The Higgs oson The Higgs oson is a qantm exitation of the Higgs fiel. In analogy, sppose an interesting rmor is shote in thr the oor. The Higgs Boson The Higgs has een preite t not oserve. How mh mass o yo think it has? The people get qite exite. They lster to pass on the rmor, an the lster propagates thr the room. Sine the information is arrie y lsters of people, an sine it was lstering whih gave extra mass to the poplar person, the lsters also have mass. Fri. May 4, 2007 Phy107 Letre A. No mass B. Light like an p or own qark C. Very massive like a top qark Fri. May 4, 2007 Phy107 Letre From the Higgs Boson to Leaelly Physiists from the Lawrene Berkeley National Laoratory are sing the same methos to searh for the elsive Higgs Boson partile an to igitally restore aio reorings from the past. Berkeley La signe an agreement with the Lirary of Congress to igitize the many thosans of early les or jazz reorings it has in its arhives. An the reslts are spetalar. The Higgs oson Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre

7 Qarks Eletron Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre Glon Design ymar Newson 1993 Charateristis: Glon Moel GLUON is fix. The seat an the ak are in steel overe with injete flameretarant polyrethane foam. The sies are in rigi polyrethane, grey laqere. The asement is in steel, laqere grey. More Unifiations? Fri. May 4, 2007 Phy107 Letre Fri. May 4, 2007 Phy107 Letre Not all that easy Fri. May 4, 2007 Phy107 Letre

Particles and fields. Today: Review Particle Physics. Question. Quantum Electrodynamics: QED. Electrons and photons

Particles and fields. Today: Review Particle Physics. Question. Quantum Electrodynamics: QED. Electrons and photons Exam 4: Fri. May 10, in-class 20 qestions, covers fission, fsion, particle physics No final exam. Essays retrne Friay Toay: Review Particle Physics Particles an fiels: a new pictre Qarks an leptons The