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Diff — LHCb

Comparing rev 1 → rev 2

	{{infobox
	\| title = LHCb
	\| image = lhcb-rich-detector.jpg
	\| caption = Detector hardware of the LHCb experiment (CERN, CC BY-SA 3.0)
	\| full_name = Large Hadron Collider beauty experiment
-	\| location = CERN, LHC interaction point 8 — Ferney-Voltaire, France, ~100 m underground
+	\| location = CERN, LHC interaction point 8 — Ferney-Voltaire, France, deep underground
	\| purpose = Studies beauty (bottom) quarks — rare decays, CP violation, matter–antimatter asymmetry
	\| design = Single-arm forward spectrometer — catches the forward-scattered beauty particles
	\| data = ~100 million proton collisions/second after Upgrade I; ~4 TB/s throughput
	\| claims_to_fame = Pentaquark discovery (2015) · Bₛ → μμ observation (2015) · B⁰ → μμ evidence (Nov 2026 — the [[zeptoverse]])
	}}

	The LHCb experiment (Large Hadron Collider beauty) is the LHC's specialist in the strange and the rare — the detector built to watch beauty quarks decay in the instant between their creation and their disappearance. Where the LHC's two general-purpose giants, ATLAS and CMS, hunt the headline discoveries (the Higgs was theirs), LHCb operates in a different register: it catalogs the unlikely — the one-in-a-billion decay, the asymmetry between matter and antimatter — and from those deviations extracts physics the big detectors cannot reach. On 3 November 2026 it produced its most famous result: evidence for the rarest decay ever observed, the event that opened the [[zeptoverse]].[[cite: CERN; LHCb collaboration]]

	## Why a beauty experiment

	Beauty (bottom) quarks are ideal laboratories for precision physics: they're heavy enough to decay through rich channels, they're produced copiously in LHC collisions, and their decays are exquisitely sensitive to CP violation — the matter–antimatter asymmetry that any answer to [[why does matter exist]] must produce. Where a detector like ATLAS surrounds the collision point in all directions, LHCb is a forward spectrometer: a 20-metre tunnel of instruments pointed down-beam, because proton collisions tend to send beauty particles shooting forward rather than spraying sideways. Its vertex detector sits millimetres from the beam, close enough to catch particles that live a trillionth of a second by the millimetres they travel before dying.[[cite: LHCb detector design documentation]]

	## What it's found

	* The pentaquark (2015) — a new kind of hadron: five quarks bound together, predicted but never seen before LHCb; later analysis split it into a family of pentaquark states
	* Bₛ → μμ (2015, jointly with CMS) — first observation of the ultra-rare beauty-meson decay to two muons, ~3 per billion — the predecessor to the November 2026 result
	* Dozens of new tetraquark and exotic hadron states — LHCb has become the world's factory of "molecules made of quarks"
	* CP violation in baryons (2025) — first observation of matter–antimatter asymmetry in a baryon (a three-quark particle), opening a new front in the baryogenesis mystery
	* B⁰ → μμ (November 2026) — evidence for the rarest decay ever observed, ~1 in 10 billion, at 3.2 sigma — the measurement that opened the [[zeptoverse]]; see [[one in ten billion decay]][[cite: LHCb publications; CERN announcements]]

	## The Upgrade I rebuild

-	The 2026 result was possible because LHCb rebuilt itself. Upgrade I, completed over the 2022–2024 shutdown, replaced nearly every detector component: a new silicon vertex detector (VELOpix) closer to the beam, new tracking stations, and a trigger moved entirely to software — replacing fixed-hardware filters with a real-time GPU farm that inspects every collision at ~30 MHz. The upgraded machine records ~100 million proton collisions per second, five times its old rate, with machine-learning classifiers that can find a one-in-ten-billion event in a firehose of ~4 terabytes per second. Without the rebuild, the B⁰ → μμ signal would have stayed below the noise floor.[[cite: LHCb Upgrade I documentation; INFN]]
+	The 2026 result was possible because LHCb rebuilt itself. Upgrade I, installed during the LHC's second long shutdown and recording data since 2024, replaced nearly every detector component: a new silicon vertex detector (VELOpix) closer to the beam, new tracking stations, and a trigger moved entirely to software — replacing fixed-hardware filters with a real-time GPU farm that inspects every collision at ~30 MHz. The upgraded machine records ~100 million proton collisions per second, five times its old rate, with machine-learning classifiers that can find a one-in-ten-billion event in a firehose of ~4 terabytes per second. Without the rebuild, the B⁰ → μμ signal would have stayed below the noise floor.[[cite: LHCb Upgrade I documentation; INFN]]

	## How it relates to the other detectors

	The LHC rings four major experiments at four collision points: ATLAS and CMS (the generalists — Higgs, new particle searches), ALICE (heavy-ion collisions and quark-gluon plasma), and LHCb (the specialist — beauty physics and precision flavor measurements). They are complementary by design: the generalists find new particles; LHCb tests whether the known ones obey the rules. Both modes are needed — the [[zeptoverse]] result is exactly the kind of finding only a dedicated flavor experiment could produce.[[cite: LHC experiment documentation]]

	## See also

	* [[zeptoverse]] — the realm LHCb opened
	* [[one in ten billion decay]] — its most famous result
	* [[why does matter exist]] — the problem LHCb's physics addresses
	* [[history of physics]]

	## References

	- LHCb collaboration — detector description, JINST 3 S08005
	- CERN — LHCb Upgrade I documentation
	- LHCb collaboration — pentaquark discovery (2015); Bₛ → μμ with CMS (2015); baryon CP violation (2025)
	- CERN — "LHCb finds evidence of one-in-ten-billion particle decay" (Nov 2026)

	[[Category:Science]]
	[[Category:Physics]]
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