A Bump At Lep Almost \(30\Gev\): Weak But Perhaps Justifiable

Update: This article was mentioned at The Wire inwards India. I believe it's a dainty article except that, equally Tommaso Dorigo pointed out, has some incorrect numbers translating 3 sigma to probabilities etc.

In the morning, I was intrigued yesteryear a hep-ex newspaper yesteryear Arno Heister

Observation of an excess at \(30\GeV\) inwards the contrary sign di-muon spectra of \(Z\to b\bar b+X\) events recorded yesteryear the ALEPH experiment at LEP

To brand the even out short, he claims that the 1992-1995 information from the LEP (Large Electron-Positron) Collider at CERN contains a less-than-3-sigma bump at \(M_{\mu^+\mu^-}\sim 30.4\GeV\) indicating a boson of width \(1.8\GeV\).



Recall that the LHC is located inwards a tunnel that was the largest European infrastructure projection earlier it was surpassed yesteryear the Channel Tunnel. But the LHC isn't the root collider that has lived or lives inwards the LHC tunnel. Before it was born, the LEP collider – that used to collide electrons amongst positrons – was happily living there.

The vocal higher upward shows what LEP looked similar to the horny girlfriends of (male and female) particle physicists. However, if y'all dared to claim that at that spot was no LHC inwards the tunnel, y'all would hold upward wrong. The really vocal was sung (in 2000) yesteryear the LHC, the Les Horribles Cernettes. ;-)




I was hesitating whether the bump deserves a weblog postal service but I decided that the reply is Yes afterward I saw Matt Strassler's text

A Hidden Gem At An Old Experiment?

minutes ago. Strassler starts yesteryear maxim that acre he admires the word of Sabine Hossenfelder – who trumps most chimps that Strassler knows – she is completely incorrect when she says that the nightmare scenario has come upward true. After all, Strassler points out, at that spot can't hold upward whatsoever nightmare because it's non fifty-fifty a nighttime yet.




When he gets to the technicalities, it becomes clear that the events pointed out yesteryear Arno Heister are events that comprise a muon pair, \(\mu^+\mu^-\), or an electron-positron pair, \(e^+ e^-\), along amongst the bottom quark-antiquark pair, \(b\bar b\). The invariant volume of the leptons \(\ell^+\ell^-\) is measured too the bump is works life close \(30\GeV\), around one-third of the Z-boson mass.



But on top of the lepton pair, the events are requested to comprise the bottom quarks. So the catch is that y'all can't run into these novel hypothetical bosons decaying to the lepton duo inwards isolation. You may solely run into them along amongst some other novel particle that decays to the quark-antiquark pair.

Matt Strassler says (and said a decade ago) that this is rather natural inwards the "hidden valley" models. Those may predict a novel spin-one (vector) boson \(V\), amongst the volume of \(30\GeV\) if y'all desire to explicate these events; along amongst a novel spin-zero (scalar) boson \(S\) which decays to \(b\bar b\) too sometimes mayhap to \(\tau^+\tau^-\).

Both novel particles \(V\) too \(S\) may arise from the decay of\[

Z \to V + S

\] the adept onetime Z-boson whose volume is \(91\GeV\). So inwards the electron-positron collisions, the Z-boson could bring been created. This Z-boson could bring decayed to 2 (new) bosons \(V,S\) too those decayed to the lepton duo too the quark-antiquark pair, respectively.

However, I give away the whole shape of "hidden valley" models rather unmotivated. Just to hold upward sure, it's non incorrect or inconsistent – similar loop quantum gravity or other slice of debunkable garbage that I bring repeatedly written about. But I don't experience that they're needed for anything, that at that spot genuinely exists prove that they should hold upward right. There's no strong prove that they shouldn't exist, either. But if y'all similar to role some Occam's razor, y'all could intend that at that spot is a adept argue – the razor – to prefer the Standard Model (or MSSM) over the "hidden valley" models. On the other hand, razors may hold upward dangerous. You may cutting your pharynx if y'all role them unwisely.

The "hidden valleys" may occur but if they do, 1 may ask: Who ordered them?

It's genuinely difficult to extract a reasonable guess from Matt Strassler of the probability that the "hidden valley" models are relevant for Nature – or fifty-fifty relevant for those item bumps at ALEPH (one of the detectors at LEP, i.e. a counterpart of ATLAS too CMS at the LHC) that are beingness talked virtually here. Why?

Because Matt Strassler is, along amongst Kathryn Zurek too 2 or too then less of import collaborators, a co-father of the "hidden valleys". See Strassler-Zurek 2006. In fact, the root 3 references inwards Heister's newspaper are papers written or co-written yesteryear Matt Strassler. Of course, a blogger's proposed gear upward of novel particles may hold upward real. But worries virtually the blogger's impartiality may potentially hold upward justified, too.

OK, can't the existence of the novel \(30\GeV\) boson hold upward settled yesteryear the LHC?



The subject vocal from "Friends of the Green Valley", a Czechoslovak communist-era lather opera virtually kids (of my age, at that time) who befriend wild animals cheers to a gamekeeper. Just to hold upward sure, the subject vocal inwards Czech is sung yesteryear a non-musician thespian who is Slovak, to brand things worse.

It seems to me that Strassler basically says that the number of collisions at the LHC is to a greater extent than than plenty to create too then but the 6,000 LHC experimenters haven't genuinely done a search for the channel equivalent to Heister's newspaper – or many other searches for the "hidden valleys" that should hold upward done. I am somewhat surprised yesteryear this claim but it's plausible.

It would for certain hold upward exciting inwards the medium term if this novel physics were found. However, inwards the long run, I wouldn't know what to create amongst that. I intend that the effective plain theory describing all of our experiments inwards Nature would larn "more messy" too "more urgently waiting for answers", non less so. The "hidden valleys" could bring far-reaching consequences for our guesses virtually the shape of compactified dimensions inwards string theory too related high-energy issues. But I bring some worries that the anthropic hand-waving too "typicality" could hold upward our best explanation why the hidden valleys be at all too why they bring the stone oil properties they have. That could amplify some features of the status quo that some people give away frustrating.