From dff92c253a78801ef4f8795b054363848f76a502 Mon Sep 17 00:00:00 2001
From: Maximilian Reininghaus <maximilian.reininghaus@kit.edu>
Date: Fri, 21 Dec 2018 15:16:59 +0100
Subject: [PATCH] commented testCOMBoost
---
Framework/Utilities/testCOMBoost.cc | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/Framework/Utilities/testCOMBoost.cc b/Framework/Utilities/testCOMBoost.cc
index 353fdaee..782fcf90 100644
--- a/Framework/Utilities/testCOMBoost.cc
+++ b/Framework/Utilities/testCOMBoost.cc
@@ -39,33 +39,42 @@ TEST_CASE("boosts") {
return E * E / cSquared - p.squaredNorm();
};
- MassType const projectileMass = 4_GeV / cSquared;
- Vector<momentum_d> pProjectileLab{rootCS, {0_GeV / c, 100_GeV / c, 0_GeV / c}};
+ // define projectile kinematics in lab frame
+ MassType const projectileMass = 1._GeV / cSquared;
+ Vector<momentum_d> pProjectileLab{rootCS, {0_GeV / c, 1_PeV / c, 0_GeV / c}};
EnergyType const eProjectileLab = energy(projectileMass, pProjectileLab);
+ // define target kinematics in lab frame
MassType const targetMass = 1_GeV / cSquared;
Vector<momentum_d> pTargetLab{rootCS, {0_Ns, 0_Ns, 0_Ns}};
EnergyType const eTargetLab = energy(targetMass, pTargetLab);
+ // define boost to com frame
COMBoost boost(eProjectileLab, pProjectileLab, targetMass);
+ // boost projecticle
auto const [eProjectileCoM, pProjectileCoM] =
boost.toCoM(eProjectileLab, pProjectileLab);
+
+ // boost target
auto const [eTargetCoM, pTargetCoM] = boost.toCoM(eTargetLab, pTargetLab);
+ // sum of momenta in CoM, should be 0
auto const sumPCoM = pProjectileCoM + pTargetCoM;
+ CHECK(sumPCoM[2] / (1_GeV / c) == Approx(0).margin(absMargin));
+ // mandelstam-s should be invariant under transformation
CHECK(s(eProjectileLab + eTargetLab,
pProjectileLab.GetComponents() + pTargetLab.GetComponents()) /
(1_GeV / c) / (1_GeV / c) ==
Approx(s(eProjectileCoM + eTargetCoM, pProjectileCoM + pTargetCoM) / (1_GeV / c) /
(1_GeV / c)));
- CHECK(sumPCoM[2] / (1_GeV / c) == Approx(0).margin(absMargin));
-
+ // boost back...
auto const [eProjectileBack, pProjectileBack] =
boost.fromCoM(eProjectileCoM, pProjectileCoM);
+ // ...should yield original values before the boosts
CHECK(eProjectileBack / eProjectileLab == Approx(1));
CHECK((pProjectileBack - pProjectileLab).norm() / (1_GeV / c) ==
Approx(0).margin(absMargin));
--
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