lips package

Submodules

lips.particle module

class lips.particle.Particle(four_mom=None, real_momentum=False)

Describes the kinematics of a single particle.

angles_for_squares()

Flips left and right spinors.

comp_twist_x(other)
four_mom

Four Momentum with upper index: P^μ

four_mom_d

Four Momentum with lower index: P_μ

l_sp_d

Left spinor with index down: λ̅_α̇ (row vector).

l_sp_u

Left spinor with index up: λ̅^α̇ (column vector).

r2_sp

Four Momentum Slashed with upper indices: P^{α̇α}

r2_sp_b

Four Momentum Slashed with lower indices: P̅̅_{αα̇}

r_sp_d

Right spinor with index down: λ_α (column vector).

r_sp_u

Right spinor with index up: λ^α (row vector).

randomise(real_momentum=False)

Randomises its momentum.

randomise_twist()
twist_x_to_mom(other)

lips.particles module

class lips.particles.Particles(number_of_particles_or_particles=None, seed=None, real_momenta=False, fix_mom_cons=True)

Describes the kinematics of n particles. Base one list of Particle objects.

angles_for_squares()

Switches all angle brackets for square brackets and viceversa.

static check_consistency(temp_string)
cluster(llIntegers)

Returns clustered particle objects according to lists of lists of integers (e.g. corners of one loop diagram).

fix_mom_cons(A=0, B=0, real_momenta=False, axis=1)

Fixes momentum conservation using particles A and B.

four_momenta_for_mathematica(as_spinors=False)
ijk_to_3Ks(ijk)
ijk_to_3NonOverlappingLists(ijk, mode=1)
image(permutation)

Returns the image of self under a given permutation. Remember, this is a passive transformation.

insert(index, *args)
momentum_conservation_check(silent=True)

Returns true if momentum is conserved.

onshell_relation_check(silent=True)

Returns true if all on-shell relations are satisfied.

phasespace_consistency_check(invariants=[], silent=True)

Runs momentum and onshell checks. Looks for outliers in phase space. Returns: mom_cons, on_shell, big_outliers, small_outliers.

randomise_all(real_momenta=False)

Randomises all particles. Breaks momentum conservation.

randomise_twistor()
save_phase_space_point(invariant=u'')
total_mom

Total momentum of the given phase space as a rank two spinor.

lips.particles.indexing_decorator(func)

Rebases a list to start from index 1.

lips.particles_compute module

class lips.particles_compute.Particles_Compute
compute(temp_string)

Computes spinor strings.

Available variables: ⟨a|b⟩, [a|b], ⟨a|b+c|d], ⟨a|b+c|d+e|f], …, s_ijk, Δ_ijk, Ω_ijk, Π_ijk, tr5_ijkl

ee(i, j)

Contraction of two polarization tensors. Requires .helconf property to be set.

ep(i, j)

Contraction of polarization tensor with four momentum. Requires .helconf property to be set.

ldot(A, B)

Lorentz dot product: 2 trace(P^{α̇α}P̅̅_{αα̇}) = P_A^μ * η_μν * P_B^ν.

pe(i, j)

Contraction of four momentum with polarization tensor. Requires .helconf property to be set.

lips.particles_set module

class lips.particles_set.Particles_Set
set(temp_string, temp_value, fix_mom=True, mode=1, itr=2, prec=0.1)

Constructs a given collinear limit phase space.

lips.particles_set_pair module

class lips.particles_set_pair.Particles_SetPair
set_pair(t_s1, t_v1, t_s2, t_v2, itr=10, prec=0.1)

Constructs a double collinear limit phase space.

Module contents

Defines tools for phase space manipulations. Particles objects are base one lists of Particle objects.

Particles objects allow to:

  1. Compute spinor strings, through .compute;
  2. Construct single collinear limits, through .set;
  3. Construct double collinear limits, through .set_pair.
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oParticles = Particles(multiplicity)
oParticles.randomise_all()
oParticles.fix_mom_cons()
oParticles.compute(spinor_string)
oParticles.set(spinor_string, small_value)
oParticles.set_pair(spinor_string_1, small_value_1, spinor_string_2, small_value_2)