<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>K</mml:mi></mml:mrow><mml:mrow><mml:mi>L</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo>→</mml:mo><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi></mml:math>: Theory and phenomenology

Ma, Ernest; Pramudita, Aloysius Adya

doi:10.1103/physrevd.24.2476

Cited by 53 publications

(23 citation statements)

References 24 publications

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“…In the charm sector, however, the small mass difference between downtype quarks of the first two families translates to a large suppression at the loop level from the GIM mechanism [1]. To date, measurements of radiative decays of charm mesons are consistent with results of theoretical calculations that include both short-distance and long-distance * Now at Temple University, Philadelphia, Pennsylvania 19122, USA † Also with Università di Perugia, Dipartimento di Fisica, Perugia, Italy ‡ Now at University of South Alabama, Mobile, Alabama 36688, USA § Also with Università di Sassari, Sassari, Italy contributions and predict decay rates several orders of magnitude below the sensitivity of current experiments [3][4][5][6][7][8]. While these rates are small, it has been postulated that new physics (NP) processes can lead to significant enhancements [9].…”

supporting

confidence: 65%

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
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We search for the rare decay of the D 0 meson to two photons, D 0 → γγ, and present a measurement of the branching fraction for a D 0 meson decaying to two neutral pions, B(D 0 → π 0 π 0 ). The data sample analyzed corresponds to an integrated luminosity of 470.5 fb −1 collected by the BABAR detector at the PEP-II asymmetric-energy e + e − collider at SLAC. We place an upper limit on the branching fraction, B(D 0 → γγ) < 2.2 × 10 −6 , at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find B(D 0 → π 0 π 0 ) = (8.4 ± 0.1 ± 0.4 ± 0.3) × 10 −4 .PACS numbers: 12.15. Mm, 13.25.Ft, 14.40.Lb, 14.70.Bh I. I. INTRODUCTIONIn the Standard Model (SM) flavor-changing neutral currents (FCNC) are forbidden at tree level [1]. These decays are allowed at higher order and have been measured in the K and B meson systems [2]. In the charm sector, however, the small mass difference between downtype quarks of the first two families translates to a large suppression at the loop level from the GIM mechanism [1]. To date, measurements of radiative decays of charm mesons are consistent with results of theoretical calculations that include both short-distance and long-distance * Now at Temple University, Philadelphia, Pennsylvania 19122, USA † Also with Università di Perugia, Dipartimento di Fisica, Perugia, Italy ‡ Now at University of South Alabama, Mobile, Alabama 36688, USA § Also with Università di Sassari, Sassari, Italy contributions and predict decay rates several orders of magnitude below the sensitivity of current experiments [3][4][5][6][7][8]. While these rates are small, it has been postulated that new physics (NP) processes can lead to significant enhancements [9].In this paper we report results of a search for the FCNC decay of the neutral D meson into two photons. The only previous study was conducted by the CLEO collaboration using 13.8 fb A separate calculation using heavy quark effective theory combined with chiral perturbation theory (HQχPT) [12] reveals a similar dominance of long-distance over shortdistance (SD) effects, with the SD branching ratio esti-4 mated to be [11]In the context of the Minimal Supersymmetric Standard Model, gluino exchange can enhance the SM rate by up to a factor of 200 [9]. The large number of charm decays in the BABAR dataset provide the opportunity to study this enhancement. A 200-fold increased rate would result in approximately 1370 events in the BABAR dataset (470.5 fb −1 ) with only six events predicted from the theoretical SM branching fraction (3.5 × 10 −8 , as determined in the VMD calculation.) A summary of the relevant branching fractions is shown in Table I.In this paper we also report a new measurement of the branching fraction for the decay D 0 → π 0 π 0 , which is the dominant background in the D 0 → γγ analysis. II. II. THE BABAR DETECTOR AND DATASETThis analysis is based on a data sample corresponding to an integrated luminosity of 470.5 fb −1 collected by the BABAR detector at the SLAC PEP-II e + e − asymmetricenergy collid...

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supporting

confidence: 65%

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
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“…In our convection the sign of the ratio A(i)--+2y)l A (7T°-* 2y) is the same sign as for A(j)-+ 2y)/A (TT°-• 2y), in order to satisfy the £/-spin relation, 12 The parameter / is the fraction of the A/ = \ transition amplitude that comes from the "penguin" diagram. So for the two solutions of p -1 and p ~ 0, /=1 or -j, respectively.…”

Section: {~) ()mentioning

confidence: 93%

“…Here, we generalize the calculation of A Q in Ref. 12 to include the KM phase 8. Using their results for A h we find that the quark contribution is rather small,…”

Section: {~) ()mentioning

confidence: 99%

K0,(K¯0)→
Chau¹,
Cheng²
1985
Phys. Rev. Lett.
41
1
12
0
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The mixing and the CP-nonconserving effects are studied for K°, K -+ 2y. The Kobayashi-Mashawa scheme can give observable CP-nonconserving effects different from those of the superweak interaction. Experimental ways to detect such effects are pointed out.It has been twenty years since the first observation 1 of CP nonconservation, K L -* 2TT, and the charge asymmetry of K L -• irev were reported. So far these are still the only instances of CP nonconservation observed. Further, both phenomena originatejrom the same CP-nonconserving source, the K 0± =* K° transition in the mass matrix. CP-nonconserving effects can also arise from weak decay amplitudes. A nonzero e' would be such an effect. 2 " 4 Unfortunately, A/ = -j dominance gives e' a suppression factor of twenty as compared to e, |e'| < Ie |/20. Recent analyses in the Kobayashi-Maskawa (KM) scheme of CP nonconservation have shown that such CP-nonconserving effects from decay amplitudes can be significant in b decays, 5 giving partial-decay-rate differences between particles and their antiparticles. It would be interesting to see if there are other such decay-amplitude CP-nonconserving effects in the K decays. The K -• 2y is such a candidate, especially since the rate for K L -* 2y is about one-half the rate of K L -• 7r°7r°. Here, we give a detailed analysis of CP-nonconserving effects in (-) K °-• 2y in the KM scheme. Special attention is paid to how the decay-amplitude effects can be distinguished from the mass-matrix effects. The latter can be calculated precisely from the measured CPnonconservation effects of K L -• 2TT and K L -* ire v. We shall show that, on the basis of current order-ofmagnitude estimates, the decay-amplitude CPnonconserving effects in the KM scheme can be significant, giving a 0.1% to 0.2% effect comparable to that from the pure mass-matrix effects in the partialdecay-rate difference. We then discuss the possible ways to detect such effects. Our calculations and conclusions are substantially different from those of a recent analysis by Decker, Pavlopoulos, and Zoupanos. 6 These differences will be discussed at the end of the paper.Formulation.-The two-photon system is a mixture of the CP-even state, 2y + , and the CP-odd state, 2y_. The decay rates are given by

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“…2 To convert G%G°V into a glueball, we parametrize (0\a s GZ v G2 v \G°)=f G m£ (5) Using the QCD sum-rule results from Ref. 8, fc is equal to -0.242 GeV for m G « 1.4 GeV.…”

Section: (A) and Is Given Bymentioning

confidence: 99%

“…! ' 2 One only needs to change the coupling of the quark-photon vertex eqy^qA^ to the quark-gluon vertex g s qr^a/2qG^…”

mentioning

confidence: 99%

Glueball contribution toKL→2γ and its possible detection inDsde

Pakvasa

Paschos

et al. 1990

Phys. Rev. Lett.

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Considering the i(1460) to be the physical glueball G and to mix with r?', we then find the mixing angle to be restricted to 0.15>sin#2> -0.43 from the data of /r°,r7,r;'--• 2y and the upper bound on i(l460)-* 2y. The transition matrix element for KL -* G° (bare glueball) is also computed (and found to be comparable to that for KL-*-JT°). These permit the glueball contribution to KL -+ 2/ and AmK L -K s to be significant. Finally, for large mixing angles, the decay of Z) 5 + into a glueball is sizable, e.g., B(D S + -• K1460)TT + ) can be as large as 1%, and searches for glueballs in these decays are highly desirable.

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KL→γγ: Theory and phenomenology

Cited by 53 publications

References 24 publications

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
View full text Add to dashboard Cite

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
View full text Add to dashboard Cite

K0,(K¯0)→
Chau¹,
Cheng²
1985
Phys. Rev. Lett.
41
1
12
0
View full text Add to dashboard Cite

Glueball contribution toKL→2γ and its possible detection inDsde

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KL→γγ: Theory and phenomenology

Cited by 53 publications

References 24 publications

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0Lees1, Poireau2, Prencipe3 et al. 2012Phys. Rev. D27160View full textAdd to dashboardCite

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0Lees1, Poireau2, Prencipe3 et al. 2012Phys. Rev. D27160View full textAdd to dashboardCite

K0,(K¯0)→Chau1, Cheng2 1985Phys. Rev. Lett.411120View full textAdd to dashboardCite

Glueball contribution toKL→2γ and its possible detection inDsde

Contact Info

Product

Resources

About

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
View full text Add to dashboard Cite

Search for the decayD0→γγand measurement of the branching fraction forD0→π0π0
Lees¹,
Poireau²,
Prencipe³
et al. 2012
Phys. Rev. D
27
1
6
0
View full text Add to dashboard Cite

K0,(K¯0)→
Chau¹,
Cheng²
1985
Phys. Rev. Lett.
41
1
12
0
View full text Add to dashboard Cite