Observation of direct soft photon production in π−p interactions at 280 GeV/c

Banerjee, S.; Barberis, D.; Belogianni, A.; Beusch, W.; Brodbeck, T. J.; French, B. R.; Goldschmidt‐Clermont, Y.; Grabowski, Maciej; Kerres, U.; Knudson, K.; Morris, J. A. G.; Perepelitsa, V.; Quercigh, E.; Sonderegger, P.; Spyropoulou‐Stassinaki, M.; Subramanian, A.; Vassiliadis, G.; Vichou, I.; Weigend, A.; Wilson, G. W.

doi:10.1016/0370-2693(93)91126-8

Cited by 47 publications

(57 citation statements)

References 9 publications

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“…Therefore, when using detected particle spectra in the bremsstrahlung calculations, formula (2) is more stable with respect to the particle loss and measurement errors as compared to the standard one. Moreover, even in the case of using precise Monte Carlo spectra for the calculations, as was done in [1,[11][12][13][14]22], the implementation of formula (2) should be preferred in computing the bremsstrahlung as giving smaller fluctuations of the sum terms for the specific particle and photon momentum configurations leading to extremely low values of denominators in formula (2) (so called collinear singularity).…”

Section: Bremsstrahlung Calculationsmentioning

confidence: 99%

“…Turning to the models exploiting collective behavior of radiation sources (let us call them collective models for brevity), it is interesting to note that in Barshay's model of a transient new coherent condition of matter [65][66][67][68], proposed for the explanation of the anomalous soft photon production in hadronic beam experiments [9][10][11], the soft pho-ton radiation enhancement appears also due to an explicitly non-linear feature of the model, but the radiation itself is coherent and the enhancement occurs due to a constructive interference of radiation sources [65].…”

Section: General Remarksmentioning

confidence: 99%

“…The observation of the excess of soft photons in hadronic events of Z 0 decays reported in [1] is indeed a further contribution to the collection of the anomalous soft photon effects found earlier in reactions of multiple hadron production in a e-mail: jan.timmermans@cern.ch b Deceased. several hadronic beam experiments at high energy [9][10][11][12][13][14], all at the photon c.m.s. rapidities y > 1.2.…”

Section: Introductionmentioning

confidence: 99%

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Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

Abdallah¹,

Abreu²,

Adam³

et al. 2010

Eur. Phys. J. C

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An analysis of the direct soft photon production rate as a function of the parent jet characteristics is presented, based on hadronic events collected by the DELPHI experiment at LEP1. The dependences of the photon rates on the jet kinematic characteristics (momentum, mass, etc.) and on the jet charged, neutral and total hadron multiplicities are reported. Up to a scale factor of about four, which characterizes the overall value of the soft photon excess, a similarity of the observed soft photon behavior to that of the inner hadronic bremsstrahlung predictions is found for the momentum, mass, and jet charged multiplicity dependences. However for the dependence of the soft photon rate on the jet neutral and total hadron multiplicities a prominent difference is found for the observed soft photon signal as compared to the expected bremsstrahlung from final state hadrons. The observed linear increase of the soft photon production rate with the jet total hadron multiplicity and its strong dependence on the jet neutral multiplicity suggest that the rate is proportional to the number of quark pairs produced in the fragmentation process, with the neutral pairs being more effectively radiating than the charged ones.

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Section: Bremsstrahlung Calculationsmentioning

confidence: 99%

Section: General Remarksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

Abdallah¹,

Abreu²,

Adam³

et al. 2010

Eur. Phys. J. C

Self Cite

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“…The inclusive production of soft photons in particle collisions at high energies has been studied in several experiments [1][2][3][4][5][6][7][8][9] using various experimental techniques.…”

Section: Introductionmentioning

confidence: 99%

“…The SOPHIE/WA83 experiment [8], which was performed at the CERN SPS, used the OMEGA spectrometer supplemented with two electromagnetic calorimeters. It differed in three important respects from the previous two hadronic collision experiments [2,7] that saw the anomalous soft photon signal.…”

Section: Introductionmentioning

confidence: 99%

Consistency of data on soft photon production in hadronic interactions

Lichard

1994

Phys. Rev. D

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The glob model of Lichard and Van Hove and the modified soft annihilation model (MSAM) of Lichard and Thompson are used as a phenomenological tool for relating results from various experiments on soft photon production in high energy collisions. The total phenomenological expectation is composed of contributions from classical bremsstrahlung, the soft annihilation model and the glob model. The empirical excess above the background from hadronic decays at very small longitudinal momenta of photons is well reproduced, as well as that for transverse momenta p T > ∼ 10 MeV/c. Some data do not require the glob model and MSAM components in the phenomenological mixture, but do not exclude them. On the basis of consistency of all data with the total theoretical expectation we argue that the results of all experiments are mutually consistent. The models are unable to describe the excess of ultrasoft photons (p T < ∼ 10 MeV/c), seen by some, but not all, experiments. This may indicate an as yet unknown projectile-mass-dependent production mechanism. Possible relations of soft photon production to other phenomena are discussed. A simple-to-use, but physically equivalent version of the glob model is developed, which enables an easy check of presented results.

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Some properties of a transient new coherent condition of matter formed in high-energy hadronic collisions

Barshay

Heiliger

1995

Z. Phys. C - Particles and Fields

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We investigate the dynamical possibility for the formation of a transient new coherent condition of matter in high-energy hadronic collisions. The coherent bosonic amplitude is characterized by a non-zero momentum and is sustained by P -wave interactions of quasi-pions in a dense fermionic medium.We make quantitative estimates of several essential properties: the condensate momentum and the fermionic density, the size of the coherent amplitude and the negative energy density contributed by the condensate, a characteristic proper time for the system to exist prior to breakdown into a few pions, and a characteristic extension of the system over the plane perpendicular to the collision axis. These quantities then allow us to make definite estimates of new signals: a few pions with anomalously small transverse momenta ≤ 50 MeV/c; and a possible anomalous bremsstrahlung of very soft photons with characteristic transverse momenta as low as about 4 MeV/c.

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Observation of direct soft photon production in π−p interactions at 280 GeV/c

Cited by 47 publications

References 9 publications

Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

Study of the dependence of direct soft photon production on the jet characteristics in hadronic Z 0 decays

Consistency of data on soft photon production in hadronic interactions

Some properties of a transient new coherent condition of matter formed in high-energy hadronic collisions

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