Study of the Form Factor Using the SND Detector Achasov, M. N.; Baikov, A. A.; Barnyakov, A. Yu ...
Bulletin of the Lebedev Physics Institute,
2021/3, Letnik:
48, Številka:
3
Journal Article
Recenzirano
In this paper, we present the form factor
measurement in the virtual photon mass range 1 GeV <
< 2 GeV in the
process. Measurements are based on the data acquired by the SND detector at the VEPP-2000
...collider in Novosibirsk. The obtained form factor is approximated in the vector meson dominance (VMD) model. The joint fitting of the form factor obtained in the SND and NA60 experiments is also performed.
A striking discrepancy between the results for the ratio of electric and magnetic form factors of the proton obtained by two approaches: the Rosenbluth extraction from the unpolarized cross section ...and the double-polarization measurements has led to a serious re-examination of the role played by two-photon exchange diagrams. The evaluation of such diagrams could not be done in model-independent way, which means an experimental verification is required. One of the direct ways to do this is to measure the ratio of positron-proton and electron-proton elastic scattering cross-sections for identical kinematics. Such a measurement has been performed at the VEPP-3 storage ring at Novosibirsk. There were two runs at beam energies of 1.6 and 1.0 GeV at several ranges of scattering angle. The measurements covered the transferred momentum Q2 up to 1.5 GeV2 and the virtual photon polarization parameter ϵ down to 0.2 . The VEPP-3 experimental approach is described and the results of the measurements are presented.
The process
e
+
e
-
→
n
n
¯
is studied in the experiment at the VEPP-2000
e
+
e
-
collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) electromagnetic ...calorimeter is used to select
n
n
¯
events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A method for circular e−/e+ accelerator beam energy measurement is proposed. A coordinate of an electron (or a positron) in a focusing magnetic spectrometer built in a circular accelerator depends on ...its energy, two spectrometer parameters, and the circulating beam energy. The spectrometer parameters can be determined using minimum electron energies from Compton backscattering with two laser wavelengths, and a coordinate detector for photons. The photon detector is calibrated separately at well-known beam energy. The VEPP-4M collider has appropriate equipment for the method implementation: built-in focusing magnetic spectrometer, Compton calibration system with two lasers and a photon coordinate detector. Thus, the proposed technique could be implemented with minimum efforts; tests and further upgrade are planned. The beam energy can be defined with expected uncertainty better than 10−4.
The tagging system of the KEDR detector is a symmetrical focusing magnetic spectrometer for electrons and positrons scattered at small angles; it is embedded into the lattice of the VEPP-4M collider ...and intended for two-photon processes study. It measures scattered electron energy with resolution ΔE/E0=0.03% 0.6% (E0 is the beam energy). For precise energy scale calibration two methods are used: tagging of bremsstrahlung electron/positron by the photon energy measured by BGO calorimeter, and direct calibration using Compton backscattering spectrum edge. This report covers design and current status of the calibration system.
Abstract
Using the 1.32
$$\hbox {pb}^{-1}$$
pb
-
1
statistics collected at the
$$J/\psi $$
J
/
ψ
peak with the KEDR detector at the VEPP-4M
$$e^{+}e^{-\, }$$
e
+
e
-
collider, we measured the ...branching fractions of
$$J/\psi $$
J
/
ψ
meson decays to the final states 2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
K
+
K
-
π
+
π
-
π
0
, 2(
$$\pi ^{+}\pi ^{-})$$
π
+
π
-
)
and
$$K^{+}K^{-}\pi ^{+}\pi ^{-}$$
K
+
K
-
π
+
π
-
. The results obtained for the decays
$$J/\psi \rightarrow $$
J
/
ψ
→
2(
$$\pi ^{+}\pi ^{-})\pi ^{0}$$
π
+
π
-
)
π
0
,
$$J/\psi \rightarrow K^{+}K^{-}\pi ^{+}\pi ^{-}\pi ^{0}$$
J
/
ψ
→
K
+
K
-
π
+
π
-
π
0
contradict the measurements performed by other groups in the last century, but agree well with recent results of BABAR and BESIII collaborations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Measurement of the integrated luminosities of the data taken by BESⅢ at √s=3.650 and 3.773 GeV 麦迪娜 M. N. Achasov O. Albayrak D. J. Ambrose 安芬芬 安琪 白景芝 R. Baldini Ferroli 班勇 J. Becker J. V. Bennett M. Bertani 边渐鸣 E. Boger O. Bondarenko I. Boyko S. Brauna R. A. Briere V. Bytev 蔡浩 蔡啸 O. Cakir A. Cnlcaterra 曹国富 S. A. Cetin 常劲帆 G. Chelkov 陈刚 陈和生 陈江川 陈玛丽 陈申见 陈旭荣 陈元柏 程和平 初元萍 D. Cronin-Hennessy 代洪亮 代建平 D. Dedovich 邓子艳 A. Denig I. Denysenko M. Destefanis 丁伟民 丁勇 董燎原 董明义 杜书先 方建 房双世 L. Fava 封常青 P. Friede 傅成栋 傅金林 O. Fuks 高原宁 耿聪 K. Goetzen 龚文煊 W. Gradl M. Greco 顾旻皓 顾运厅 管颖慧 郭爱强 郭立波 郭暾 郭玉萍 韩艳良 F. A. Harris 何康林 何苗 何振亚 T. Held 衡月昆 侯治龙 胡琛 胡海明 胡继峰 胡涛 黄光明 黄光顺 黄金书 黄亮 黄性涛 黄勇 T. Hussain 姬长胜 纪全 姬清平 季晓斌 季筱璐 姜丽丽 江晓山 焦健斌 焦铮 金大鹏 金山 景繁凡 N. KMantar-Nayestanaki M. Kavatsyuk B. Kloss B. Kopf M. Kornicer W. Kuehn 赖蔚 J. S. Lange M. Lara P. Larin M. Leyhe 李春花 李澄 李翠 李德民 李飞 李刚 李海波 李家才 李康 李蕾 李培荣 李秋菊 李卫东 李卫国 李晓玲 李小男 李学潜 李秀荣 李志兵 梁昊 梁勇飞 梁羽铁 廖广瑞 D. X. Lin(Lin) 刘北江 C. L. Liu 刘春季 刘福虎 刘芳 刘峰 刘宏邦 刘汇慧 刘怀民 刘觉平 刘凯 刘魁勇 刘佩莲 刘倩 刘树彬 刘翔 刘玉斌 刘振安 刘志强 刘智青 H. Loehner 娄辛丑 鲁公儒 吕海江 吕军光 吕晓睿 卢云鹏 罗成林 罗民兴 T. Luo 罗小兰 吕蒙 马凤才 马海龙 马秋海 马斯 马天 马骁妍 F. E. Maas M. Maggiora Q. A. Malik 冒亚军 毛泽普 J. G. Messchendorp 闵建 闵天觉 R. E. Mitchell 莫晓虎 H. Moeini C. Morales Morales K. Moriya N. Yu. Muchnoi H. Muramatsu Y. Nefedov I. B. Nikolaev 宁哲 S. Nisar 馬鹏 欧阳群 S. Pacetti J. W. Park M. Pelizaeus 彭海平 K. Peters 平加伦 平荣刚 R. Poling E. Prencipe 祁鸣 钱森 乔从丰 秦丽清 秦小帅 秦瑶 秦中华 邱进发 K.H. Rashid C. F. Redmer 荣刚 阮向东 A. Sarantsev 邵明 沈成平 沈肖雁 盛华义 M. R. Shepherd 宋维民 宋新颖 S. Spataro B. Spruck 孙功星 孙俊峰 孙胜森 孙勇杰 孙永昭 孙志嘉 孙振田 唐昌建 唐晓 I. Tapan E. H. Thorndike D. Toth M. Ullrich I. Uman G. S. Varner 王斌 王东 王大勇 王科 王亮亮 王灵淑 王萌 王平 王佩良 王庆娟 王思广 王雄飞 汪晓莲 Y. D. Wang(Yadi) 王贻芳 王亚乾 王铮 王志刚 王志宏 王至勇 魏代会 韦江波 P. Weidenkaff 文群刚 文硕频 M. Wernera U. Wiedner 伍灵慧 吴宁 吴硕星 吴蔚 吴智 夏力钢 夏宇 肖振军 谢宇广 修青磊 许国发 徐庆君 徐庆年 徐新平 许志蕊 薛镇 严亮 鄢正标 闫文成 颜永红 杨洪勋 杨迎 杨永栩 叶桦 叶梅 叶铭汉 俞伯祥 喻纯旭 于海旺 俞洁晟 于帅鹏 苑长征 袁野 A. A. Zafar A. Zallo 臧石磊 曾云 张丙新 张炳云 张驰 张长春 张达华 张宏浩 章红宇 张敬庆 张家文 张建勇 张景芝 张丽丽 张书华 张晓杰 张学尧 张瑶 张银鸿 张子平 张振宇 张正好 赵光 赵京伟 赵雷 赵玲 赵明刚 赵强 赵书俊 赵天池 赵祥虎 赵豫斌 赵政国 A. Zhemchugov 郑波 郑建平 郑阳恒 朱凯 朱科军 朱相雷 朱莹春 朱永生 朱自安 庄建 邹冰松 邹佳恒
Chinese physics C,
12/2013, Letnik:
37, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Data sets were collected with the BESⅢ detector at the BEPCⅡ collider at the center-of-mass energy of √s=3.650 GeV during May 2009 and at √s=3.773 GeV from January 2010 to May 2011. By analyzing the ...large angle Bhabha scattering events, the integrated luminosities of the two data sets are measured to be (44.49±0.02±0.44) pb-1 and (2916.94±0.18±29.17) pb-1, respectively, where the first error is statistical and the second error is systematic.
A laser polarimeter at the VEPP-4M storage ring is being developed for the beam energy calibration by the resonant depolarization method in the future high-precision measurements of the Υ meson ...masses with the KEDR detector. The status of the laser polarimeter and first energy measurements at 4.1 GeV with an accuracy of 50 keV is described.