#include <quantumnumbers.h>

A container for storing conserved values.

QuantumNumbers can be used to compare all values that should be conserved during the evolution, in particular for the whole system at fixed intervals, or for a subset of particles before- and after a DecayAction / ScatterAction / Action.

QuantumNumbers can also be used to store, and retrieve, the total value of the quantum numbers in e.g. a ScatterAction, before distributing it to the new particles.

Currently, momentum conservation (including energy conservation), charge-, isospin3-, (net-) strangeness-, (net-) bottomness-, (net-) charmness- and (net-) baryon number conservation are checked. (It should be noted, or repeated, that only the net quantities are conserved, hence this is what is stored and compared with this class.)

Usage

QuantumNumbers before(particlelist);
do_something_with(particlelist);
QuantumNumbers after(particlelist);
printf("%s", before.report_deviations(after).c_str());
if (before != after) {
  throw std::runtime_error(before.report_deviations(after));
}

Definition at line 53 of file quantumnumbers.h.

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Public Member Functions
	QuantumNumbers ()
	Construct QuantumNumbers collection with all fields 0. More...

	QuantumNumbers (const FourVector &m, const int q, const int i3, const int s, const int c, const int b, const int B)

	QuantumNumbers (const Particles &particles)
	Construct QuantumNumbers collection from the conserved quantities found in a set of particles. More...

	QuantumNumbers (const ParticleList &part)
	Construct QuantumNumbers collection from a particle list. More...

void	add_values (const ParticleData &p)
	Add the quantum numbers of a single particle to the collection. More...

FourVector	momentum () const

int	charge () const

int	isospin3 () const

int	strangeness () const

int	charmness () const

int	bottomness () const

int	baryon_number () const

bool	operator== (const QuantumNumbers &rhs) const

bool	operator!= (const QuantumNumbers &rhs) const
	Logical complement of QuantumNumbers::operator==. More...

QuantumNumbers	operator- (const QuantumNumbers &rhs) const

std::string	report_deviations (const Particles &particles) const
	Checks if the current particle list has still the same values and reports about differences. More...

std::string	report_deviations (const QuantumNumbers &rhs) const
	Reports on deviations between two QuantumNumbers collections. More...

Private Attributes
FourVector	momentum_
	Total momentum four-vector [GeV]. More...

int	charge_
	Total charge. More...

int	isospin3_
	Total isospin-3. More...

int	strangeness_
	Total strangeness. More...

int	charmness_
	Total charm. More...

int	bottomness_
	Total bottom. More...

int	baryon_number_
	Total baryon number. More...

Constructor & Destructor Documentation

◆ QuantumNumbers() [1/4]

smash::QuantumNumbers::QuantumNumbers ( )

inline

Construct QuantumNumbers collection with all fields 0.

Definition at line 56 of file quantumnumbers.h.

       : momentum_(0., 0., 0., 0.),
         charge_(0),
         isospin3_(0),
         strangeness_(0),
         charmness_(0),
         bottomness_(0),
         baryon_number_(0) {}

◆ QuantumNumbers() [2/4]

smash::QuantumNumbers::QuantumNumbers	(	const FourVector &	m,
		const int	q,
		const int	i3,
		const int	s,
		const int	c,
		const int	b,
		const int	B
	)

inline

Returns: Constructed QuantumNumbers.

Parameters

[in]	m	Momentum FourVector [GeV]
[in]	q	Charge
[in]	i3	Isospin
[in]	s	Strangeness
[in]	c	Charmness
[in]	b	Bottomness
[in]	B	Baryon number

Definition at line 75 of file quantumnumbers.h.

       : momentum_(m),
         charge_(q),
         isospin3_(i3),
         strangeness_(s),
         charmness_(c),
         bottomness_(b),
         baryon_number_(B) {}

◆ QuantumNumbers() [3/4]

smash::QuantumNumbers::QuantumNumbers ( const Particles & particles )

inlineexplicit

Construct QuantumNumbers collection from the conserved quantities found in a set of particles.

Parameters

[in] particles set of particles for which quantum numbers are calculated and constructed

Returns: Constructed object.

Definition at line 92 of file quantumnumbers.h.

                                                       : QuantumNumbers() {
     for (const ParticleData& data : particles) {
       add_values(data);
     }
   }

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◆ QuantumNumbers() [4/4]

smash::QuantumNumbers::QuantumNumbers ( const ParticleList & part )

inlineexplicit

Construct QuantumNumbers collection from a particle list.

Parameters

[in] part list of particles for which quantum numbers are calculated and constructed

Returns: Constructed object.

Definition at line 104 of file quantumnumbers.h.

                                                     : QuantumNumbers() {
     for (const auto& p : part) {
       add_values(p);
     }
   }

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Member Function Documentation

◆ add_values()

void smash::QuantumNumbers::add_values ( const ParticleData & p )

inline

Add the quantum numbers of a single particle to the collection.

Parameters

[in] p particle whose quantum number is added to the collection

Definition at line 114 of file quantumnumbers.h.

                                          {
     momentum_ += p.momentum();
     charge_ += p.pdgcode().charge();
     isospin3_ += p.pdgcode().isospin3();
     strangeness_ += p.pdgcode().strangeness();
     charmness_ += p.pdgcode().charmness();
     bottomness_ += p.pdgcode().bottomness();
     baryon_number_ += p.pdgcode().baryon_number();
   }

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◆ momentum()

FourVector smash::QuantumNumbers::momentum ( ) const

inline

Returns: The total momentum four-vector. \(P^\mu = \sum_{i \in \mbox{particles}} (E_i, \vec p_i)\) [GeV]

See also: QuantumNumbers::momentum_; ParticleData::momentum()

Definition at line 131 of file quantumnumbers.h.

131 { return momentum_; }

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◆ charge()

int smash::QuantumNumbers::charge ( ) const

inline

Returns: The total electric charge. \(Q = \sum_{i \in \mbox{particles}} q_i\)

See also: QuantumNumbers::charge_; PdgCode::charge()

Definition at line 140 of file quantumnumbers.h.

140 { return charge_; }

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◆ isospin3()

int smash::QuantumNumbers::isospin3 ( ) const

inline

Returns: Twice the total isospin-3 component. \(I = \sum_{i \in \mbox{particles}} 2{I_3}_i\)

See also: QuantumNumbers::isospin3_; PdgCode::isospin3()

Definition at line 148 of file quantumnumbers.h.

148 { return isospin3_; }

◆ strangeness()

int smash::QuantumNumbers::strangeness ( ) const

inline

Returns: The total strangeness. \(S = \sum_{i \in \mbox{particles}} S_i\)

See also: QuantumNumbers::strangeness_; PdgCode::strangeness()

Definition at line 156 of file quantumnumbers.h.

156 { return strangeness_; }

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◆ charmness()

int smash::QuantumNumbers::charmness ( ) const

inline

Returns: The total charm. \(C = \sum_{i \in \mbox{particles}} C_i\)

See also: QuantumNumbers::charmness_; PdgCode::charmness()

Definition at line 164 of file quantumnumbers.h.

164 { return charmness_; }

◆ bottomness()

int smash::QuantumNumbers::bottomness ( ) const

inline

Returns: The total bottom. \(b = \sum_{i \in \mbox{particles}} b_i\)

See also: QuantumNumbers::bottomness_; PdgCode::bottomness()

Definition at line 172 of file quantumnumbers.h.

172 { return bottomness_; }

◆ baryon_number()

int smash::QuantumNumbers::baryon_number ( ) const

inline

Returns: The total baryon number. \(B = \sum_{i \in \mbox{particles}} B_i\)

See also: QuantumNumbers::baryon_number_; PdgCode::baryon_number()

Definition at line 180 of file quantumnumbers.h.

180 { return baryon_number_; }

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◆ operator==()

bool smash::QuantumNumbers::operator== ( const QuantumNumbers & rhs ) const

inline

Returns: true if all members compare true.

Parameters

rhs	Right-hand side.

In the comparison of FourVectors, a little leeway is built-in, so this does not rely on an exact comparison of floating point values.

See also: FourVector::operator==

Definition at line 191 of file quantumnumbers.h.

                                                    {
     // clang-format off
     // invariant mass of the current momentum
     const double m0_invariant = std::sqrt(std::fabs(momentum_.sqr()));
     // invariant mass of the momentum to be compared
     const double m1_invariant = std::sqrt(std::fabs(rhs.momentum_.sqr()));
     // average invariant mass
     const double avg_m_inv = 0.5 * (m0_invariant + m1_invariant);
     /* precision used to check relative error
      * 0.1 is multiplied to make the relative error check kicks in
      * for collision energies beyond 10 GeV. */
     const double precision_high = 0.1 * small_number;
     // difference in the four-momentum
     FourVector momentum_diff = momentum_ - rhs.momentum_;
     /* Check whether momentum is conserved.
      * Even if the absolute difference in each component is larger than
      * small_number, momentum is still considered to be conserved when
      * the deviation is small enough compared to the given invariant mass. */
     bool momentum_conserved = momentum_ == rhs.momentum_ ||
         (std::fabs(momentum_diff.x0()) < precision_high * avg_m_inv &&
          std::fabs(momentum_diff.x1()) < precision_high * avg_m_inv &&
          std::fabs(momentum_diff.x2()) < precision_high * avg_m_inv &&
          std::fabs(momentum_diff.x3()) < precision_high * avg_m_inv);
     return (momentum_conserved &&
             charge_ == rhs.charge_ &&
             isospin3_ == rhs.isospin3_ &&
             strangeness_ == rhs.strangeness_ &&
             charmness_ == rhs.charmness_ &&
             bottomness_ == rhs.bottomness_ &&
             baryon_number_ == rhs.baryon_number_);
     // clang-format on
   }

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◆ operator!=()

bool smash::QuantumNumbers::operator!= ( const QuantumNumbers & rhs ) const

inline

Logical complement of QuantumNumbers::operator==.

Definition at line 224 of file quantumnumbers.h.

224 { return !(*this == rhs); }

◆ operator-()

QuantumNumbers smash::QuantumNumbers::operator- ( const QuantumNumbers & rhs ) const

inline

Returns: Entry-wise difference of two sets of QuantumNumbers.

Parameters

rhs	Right-hand side.

If everything is conserved, all entries of the result should be zero.

Definition at line 233 of file quantumnumbers.h.

                                                             {
     return {momentum_ - rhs.momentum_,          charge_ - rhs.charge_,
             isospin3_ - rhs.isospin3_,          strangeness_ - rhs.strangeness_,
             charmness_ - rhs.charmness_,        bottomness_ - rhs.bottomness_,
             baryon_number_ - rhs.baryon_number_};
   }

◆ report_deviations() [1/2]

std::string smash::QuantumNumbers::report_deviations ( const Particles & particles ) const

inline

Checks if the current particle list has still the same values and reports about differences.

Parameters

[in] particles Set of particles whose quantum number is compared

Returns: String reporting the deviations.

See also: QuantumNumbers::report_deviations(const QuantumNumbers&) const

Definition at line 248 of file quantumnumbers.h.

                                                                 {
     QuantumNumbers current_values(particles);
     return report_deviations(current_values);
   }

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◆ report_deviations() [2/2]

std::string smash::QuantumNumbers::report_deviations ( const QuantumNumbers & rhs ) const

Reports on deviations between two QuantumNumbers collections.

Parameters

[in] rhs Other QuantumNumbers collection.

Returns: A string with information about the differences.

If there are no differences, the returned string is empty; else, a descriptive warning message is returned, e.g.

Conservation law violations detected (old vs. new)
Deviation in Charge:
 164 vs. 163
Deviation in Isospin 3:
 -88 vs. -90

Definition at line 18 of file quantumnumbers.cc.

                                                                            {
   if (rhs == *this) {
     return "";
   }
   std::stringstream error_msg;
   error_msg << "Conservation law violations detected (old vs. new)\n";
   if (momentum_ != rhs.momentum_) {
     error_msg << "Deviation in Four-Momentum:\n" << std::scientific;
   }
   /* programmer's note: here, I'd like to simultaneously loop over an
    * integer (for the output; so that we know which component is
    * faulty) and both the current and rhs's momentum four-vector. If
    * there is a better way to do this, feel free to implement.
    *
    * I chose mu < 4 as the breaking condition out of the vague feeling
    * that comparing integers may be faster than accessing the
    * iterators. */
   int mu = 0;
   for (auto here_iter = momentum_.cbegin(), rhs_iter = rhs.momentum_.cbegin();
        mu < 4; ++here_iter, ++rhs_iter, ++mu) {
     if (!almost_equal_physics(*here_iter, *rhs_iter)) {
       error_msg << " P_" << mu << ": " << *here_iter << " vs. " << *rhs_iter
                 << "; Δ = " << (*here_iter - *rhs_iter) << "\n";
     }
   }
   if (charge_ != rhs.charge_) {
     error_msg << "Deviation in Charge:\n " << charge_ << " vs. " << rhs.charge_
               << "\n";
   }
   if (isospin3_ != rhs.isospin3_) {
     error_msg << "Deviation in Isospin 3:\n " << isospin3_ << " vs. "
               << rhs.isospin3_ << "\n";
   }
   if (strangeness_ != rhs.strangeness_) {
     error_msg << "Deviation in Strangeness:\n " << strangeness_ << " vs. "
               << rhs.strangeness_ << "\n";
   }
   if (charmness_ != rhs.charmness_) {
     error_msg << "Deviation in Charmness:\n " << charmness_ << " vs. "
               << rhs.charmness_ << "\n";
   }
   if (bottomness_ != rhs.bottomness_) {
     error_msg << "Deviation in Bottomness:\n " << bottomness_ << " vs. "
               << rhs.bottomness_ << "\n";
   }
   if (baryon_number_ != rhs.baryon_number_) {
     error_msg << "Deviation in Baryon Number:\n " << baryon_number_ << " vs. "
               << rhs.baryon_number_ << "\n";
   }
   return error_msg.str();
 }

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Member Data Documentation

◆ momentum_

FourVector smash::QuantumNumbers::momentum_

private

Total momentum four-vector [GeV].

See also: QuantumNumbers::momentum()

Definition at line 279 of file quantumnumbers.h.

◆ charge_

int smash::QuantumNumbers::charge_

private

Total charge.

See also: QuantumNumbers::charge()

Definition at line 286 of file quantumnumbers.h.

◆ isospin3_

int smash::QuantumNumbers::isospin3_

private

Total isospin-3.

See also: QuantumNumbers::isospin3()

Definition at line 292 of file quantumnumbers.h.

◆ strangeness_

int smash::QuantumNumbers::strangeness_

private

Total strangeness.

See also: QuantumNumbers::strangeness()

Definition at line 298 of file quantumnumbers.h.

◆ charmness_

int smash::QuantumNumbers::charmness_

private

Total charm.

See also: QuantumNumbers::charmness()

Definition at line 304 of file quantumnumbers.h.

◆ bottomness_

int smash::QuantumNumbers::bottomness_

private

Total bottom.

See also: QuantumNumbers::bottomness()

Definition at line 310 of file quantumnumbers.h.

◆ baryon_number_

int smash::QuantumNumbers::baryon_number_

private

Total baryon number.

See also: QuantumNumbers::baryon_number()

Definition at line 316 of file quantumnumbers.h.

The documentation for this class was generated from the following files:

src/include/smash/quantumnumbers.h
src/quantumnumbers.cc

Usage

Public Member Functions

Private Attributes

Constructor & Destructor Documentation

◆ QuantumNumbers() [1/4]

◆ QuantumNumbers() [2/4]

◆ QuantumNumbers() [3/4]

◆ QuantumNumbers() [4/4]

Member Function Documentation

◆ add_values()

◆ momentum()

◆ charge()

◆ isospin3()

◆ strangeness()

◆ charmness()

◆ bottomness()

◆ baryon_number()

◆ operator==()

◆ operator!=()

◆ operator-()

◆ report_deviations() [1/2]

◆ report_deviations() [2/2]

Member Data Documentation

◆ momentum_

◆ charge_

◆ isospin3_

◆ strangeness_

◆ charmness_

◆ bottomness_

◆ baryon_number_